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What is Creatinine?

The most popular and consistent test for adulteration of drug tests is creatinine. Many people confuse this with creatine, but what is creatinine and how does it indicate that a drug test has been tampered with? Creatinine concentration is checked during standard urine drug tests.

What is Creatinine?

Creatinine is the primary metabolite of creatine that is produced when creatine is broken down in muscles. It is then expelled in the urine.

Since creatine is produced by the body at a consistent rate and it’s almost entirely removed from the blood stream by our kidneys it can be used to tell if our kidneys are functioning properly and also as a benchmark for the dilution of a urine sample.

Creatinine cycle
This graphic details the generation, filtering and expulsion from creatinine in the human body.

What is a Normal Level for Creatinine Testing?

The amount of creatinine in urine varies depending on a person’s age, sex, muscle mass, water intake, activity level and overall health. Individuals with more muscle mass will produce more and so will individuals with higher activity levels.

The normal range for human urine is measured in milligrams per 24 hours. The expected range is 955 to 2,936 milligrams (mg) per 24 hours for males, and 601 to 1,689 mg per 24 hours for females. For medical testing a patient is often asked to capture their urine for a 24 hour period to get a more precise reading. For drug test adulteration testing the creatinine level is just a snapshot from a single sample.

For a urine adulteration test the cutoff level for creatinine is usually very low, often <5mg per deciliter. Levels in urine lower than this cutoff are not consistent with human urine and usually indicate an individual has engaged in water loading before being tested.

creatinine activity table
This table shows the average difference in test results for individuals with varying levels of activity.

Usually for a sample that fails an adulteration test the urine will be clear and the urine sample will also have a specific gravity that falls outside the normal range (1.003 to 1.030). Some of the color can be replaced by ingesting a high level of vitamin B12, but not enough.

Levels in Blood

If a physician finds creatinine levels in someone’s urine to be abnormally low and they do not suspect adulteration they will schedule other tests to determine the cause. If levels in the blood are high this usually means there is an issue with kidney function.

The normal range for a blood test is 0.84 to 1.21 milligrams per deciliter.

Causes of Abnormal Creatinine Levels

Several diseases and scenarios can cause abnormal readings.

  • Diabetes
  • High Blood Pressure
  • High protein diet
  • Kidney infection
  • Kidney Failure
  • Kidney Stones
  • Muscular Dystrophy
  • Myasthenia Gravis
  • Kidney Damage

When testing levels physicians will instruct patients to stop taking certain medications including Cefoxitin, Trimethoprim, and Cimetidine.

There are several supplements and activities that can alter levels.

Increase Creatinine Levels

  • Vigorous Exercise – Exercise increases creatinine levels in the blood stream and urine, at least temporarily.
  • Creatine Supplements – Creatine supplements are used to fuel muscles and slow down the production of pyruvic acid. More creatine leads to more creatinine by product.
  • High Protein Diet – High protein intake has been shown to increase creatinine levels.

Reduce Creatinine Levels

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How Much Water Will Dilute a Drug Test?

The most common drug test adulteration technique is drinking water to dilute a urine sample. The variation in water expelled in urine from person to person makes it hard to detect and since the urine still comes from the subject’s body temperature strips and observation witnesses cannot detect water dilution. How much water does it take to dilute a drug test enough to pass though?

How Drug Tests Work

The first thing you need to know is how urine drug screens work. They contain antibodies that attach to metabolites in the urine of the person being tested. The test determines if the amount of antibodies which correlate to a drug in the urine are over or under a specified cutoff level.

Other testing methods determine the exact quantity of metabolites as well as several other levels such as creatinine, protein and pH. In these more advanced laboratory tests the creatinine level in the sample is a clear indication of water loading and the sample will either be corrected and normalized based on the creatinine levels in your urine or will be marked a failure for dilution outright.

12 Panel Drug Tests - Lowest Price Online
12 Panel Drug Tests – Lowest Price Online

Drug Test City drug tests are made to the same standards with the same cutoff levels as most drug tests used nationwide. Purchase our 12 panel cups to see for sure what is on a 12 panel drug test .

Past a certain point urine dilution will raise suspicions or lead to a failed test, however for someone that doesn’t drink the recommended daily allowance of water under normal circumstances drinking water can significantly lower the concentrations of metabolites in your urine without turning the urine completely clear and without failing an analysis for low creatinine levels.

Did You Know? The average person urinates between 35-50 ounces every day and makes an average of 4-10 trips to the bathroom.

Federal Recommendations for Drug Test Cutoff Levels

  • THC 50 ng/mL
  • COC 300 ng/mL
  • OPI 2000 ng/mL
  • AMP 1000 ng/mL
  • MET 1000 ng/mL
  • BZO 300 ng/mL
  • MDMA 500 ng/mL
  • MTD 300 ng/mL
  • OXY 100 ng/mL
  • BUP 10 ng/mL
  • BAR 300 ng/mL
  • TCA 1000 ng/mL

How Water Dilution for Drug Testing Works

The average healthy adult has a bladder that will comfortably hold 16 ounces or 2 cups of liquid. Water loading works by increasing the excess water in your body so the bladder will refill with excess water before the normal mixture of byproducts and the normal level of water used to expel these byproducts accumulates back into the bladder.

The timeframe of ingestion matters as much as how much water you drink. It takes between 45-120 minutes for ingested water to start pushing urine out of your body.

Urine color chart
Witnesses and technicians will expect to see some tint to your urine sample. A sample that is entirely clear is a big red flag, but even the slightest tint is acceptable in most cases.

Since a drug test captures a single photograph of your urine content, the goal of someone trying to adulterate their urine by water dilution is to have the optimum ratio of excess water and normal urine at the time they submit their test.

When it comes to urine dilution you really need to ask yourself 2 questions.

How much water can I ingest without turning my urine totally clear?

How much water will it take to reduce metabolite concentrations under the most likely cutoff levels?

How much water can I ingest without turning my urine totally clear?

It is hard to say exactly how much water you can ingest before your urine starts to come out clear because there are so many variables, but in a 1-2 hour timeframe approximately twice bladder capacity plus the amount of water your body is expelling through sweat and cellular process results in clear urine. Roughly 32 ounces of water in a 1-2 hour period will bring your urine to the point it will start to be completely clear.

A study in the Annals of Pediatric Edocrinology Metabolism found that the maximum amount of water a person should ever drink is between 27-33.8 ounces per hour. This is the maximum amount of water a healthy human body can process without causing harmful effects to electrolyte ratios.

Medical review

How much water will it take to reduce metabolite concentrations under the most likely cutoff levels?

Now that we know the level of each metabolite your urine must be under you need to know the level of the metabolite currently in your urine. You could send a urine sample off for a laboratory gas chromatography and mass spectrometry test but that would be prohibitively expensive. The best most people can do is guess.

In one study Urinary Elimination of 11-Nor-9-carboxy- 9-tetrahydrocannnabinol in Cannabis Users found that out of the 60s subjects admitted to the test they were evenly spread out between the groups of <50ng/ml, 50-150ng/ml and >150ng/ml. The studied showed that higher concentrations took much longer to eliminate detectable levels from their system.

THC drug test levels graph
As you can show the metabolite for THC is detectable far longer for heavy users.

Users that were under the 50ng/ml cutoff at the beginning routinely started passing drug tests on the first or second day. All subjects that were under the 50ng/ml cutoff had eliminated all detectable THC metabolite (<5ng/ml) by day 8. It took 15 days for half the users between 50-150ng/ml to eliminate detectable THC metabolite. 80% of users that started over 150ng/ml level still had a detectable amount of THC in their urine at the end of 30 days.

The good thing for a user wanting to pass a drug test is that instant drug tests have a 50ng/ml cutoff. That means that light users will pass a normal test in 3-7 days and the average user that starts below 150ng/ml will be able to dilute their urine by half on the 2nd day and pass a test, which is the top of the range of how much water you can ingest without turning your urine totally clear.

Is Water Dilution Illegal or Unethical?

The god news is that the optimum water content of urine to have the best chances of passing a rigorous drug test is also around the normal recommended daily allowance for water. Since you do not want your urine to be totally clear you’re aiming for a pale straw coloration that is indicative of optimum water intake.

Most people do not drink the recommended amount of water, and it also causes their urine to have longer detection times than people that stay well hydrated.

If you drink so much water that your urine is clear and your body is passing urine with low levels of creatinine it is unethical and it could also lead to punishment depending on the circumstances of your drug test. Adulterating a drug test is illegal in many states and some prosecutors would make the argument that urine diluted by drinking an excessive amount of water is a clear case of adulteration.

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What Drugs to Test Employees For

drugs employers test for

As a business owner it can be hard to decide what drugs to test employees for. Different regions have different drug problems and considerations, but there may be a one size fits all solution. When deciding what drugs to test employees for you should consider these factors:

  • What drugs are popular in the area of operation?
  • Are any drugs popular in your industry?
  • Which drugs have the most potential to negatively affect your business?
  • Which drugs can be tested for legally, economically and effectively?
  • What tests are available that are accurate and cost effective?

Most Popular Drugs Among Employees

Most popular illegal drug used in the workplace is recreational Marijuana. Over 20% of respondents of the survey admitted to using recreational marijuana during work hours. The second most common class of drug used during work hours was opiate painkillers.

Overall drug use mirrors these findings, with 4.2 million Americans reporting marijuana use and 1.8 million admitting to using prescription pain relievers in a 2013 study conducted by the National Institute of Drug Abuse.

Substances Used at Work
This graph from shows that besides alcohol marijuana is the most commonly abused drug on the job.


Over the last decade more people with full time employment have admitted to marijuana and prescription painkiller use than all other classes of drugs combined. The effects of most prescription painkillers are mild enough that employees can use them undetected.

Common Drug Tests Employers Use

The most common instant drug test used by employers in the US is the 12 Panel Drug Test Cup. There are currently only 13 drugs that have CLIA waivers available for rapid testing, so a 12 or 13 panel cup offers the most number of tests while staying in compliance for state and federal guidelines.

Many will use a Fentanyl strip (FYL) and ETG (alcohol) strip in addition to a CLIA waived 12 panel cup. These tests are for forensic use and any indication of a positive should be sent to a lab for confirmation. The fentanyl test is becoming more popular because it is commonly being used in fake pharmaceuticals and mixed with heroin to increase its potency.

Having a CLIA waived test is important because other tests will be considered high complexity and will have no legal standing whatsoever in the majority of workplaces.

CLIA Waived Drug Test Strips

  • Marijuana (THC)
  • Cocaine (COC)
  • Opiates (OPI)
  • Amphetamines (AMP)
  • Methamphetamines (MET)
  • Benzodiazepines (BZO)
  • Ecstasy (MDMA)
  • Methadone (MTD)
  • Oxycodone (OXY)
  • Buprenorphine (BUP)
  • Barbiturates (BAR)
  • Tricyclic Antidepressants (TCA)
  • Phencyclidine (PCP)

Some organizations must adhere to recommendations published by certain branches of the federal government. In the 1990s the NIDA required testing for at least 5 types of drugs to meet the requirements to be a “Drug Free Workplace”. These drugs became known as the NIDA 5 and have since been considered the bare minimum for employer drug testing.

If an organization depends on government contracts or is contracted directly with the federal government you should consult the NIDA, SAMHSA, and Drug Free Workplace acts.

At the very minimum a company should test for the 5 illicit drugs in the NIDA 5. Since it is so cost effective, there isn’t a good reason to not upgrade to the 12 panel test cup and screen for more drugs.

NIDA 5 Drug Tests

  1. Marijuana (THC)
  2. Cocaine (COC)
  3. Opiates (OPI)
  4. Amphetamines (AMP)
  5. Phencyclidine (PCP)

In the years since the NIDA 5 was released pharmaceuticals and drugs such as methamphetamine have become much more popular while PCP has fallen out of use almost entirely. Most drug testing programs have implemented changes to reflect that.

Which Drugs Have the Biggest Effect on Business

As previously mentioned in 11 Reasons Why Employers Drug Test, the average drug user has 50% more absences than a regular employee. Employees with a prescription painkiller addiction miss 200% more often than a regular employee. When it comes to turnover 25% of people employed full time have had another employer in the previous year. 36% of average drug users have had another employer in the previous year, but that number climbs to 42% for people with a prescription painkiller addiction.

Over the course of employment opiate users cost a business more consistently, but users of drugs such as methamphetamine and cocaine are prone to have major incidents that have tremendous immediate and long term effects on a business.

Which Drug Tests Are Effective

You will notice that alcohol is often listed as the most abused drug by full time employees. There are tests that can detect alcohol, but the detection period is approximately 12 hours. Since alcohol is legal an employee that had a drink the night before isn’t technically doing anything wrong. Alcohol is also easily detected by coworkers if an employee is drinking on the job without the use of a test.

Synthetic opiates do not consistently show up on Opiate assays so Oxycodone, methadone, buprenorphine and fentanyl have their own specific tests.

In regions where pharmaceutical abuse is high these tests are almost always included in an employer drug test, but in some areas the number of people using prescription drugs legally outweighs those using illegally and companies see these as a nuisance to continuously cross check. 

It is also much easier for an employee to obtain a prescription for narcotics in areas with lower rates of prescription drug abuse.

Legal Drug Use and Acceptable Use

Besides having a short detection period, alcohol is widely used legally by employees outside of work hours. It’s more culturally acceptable to drink alcohol than to abuse other illegal drugs.

Marijuana is gaining legal status in many states and is becoming more culturally acceptable in the US with every passing year. New York city recently passed a law that made it illegal to test for recreational marijuana use on a pre employment drug test.


NYC Public Advocate Jumaane Williams
New York City’s public advocate Jumaane Williams helped the resolution to ban pre employment drug testing for THC pass the City Council. The ban went into effect in March 2020.


Responsible alcohol use outside of work hours is usually considered a private matter. As marijuana becomes legal in more jurisdictions companies will need to look at their specific laws and situation and determine how to best address drug testing for THC going forward. If your company’s roles require employees to be brand ambassadors 24/7 it might be important to have a drug and alcohol policy that extends to an employee’s personal time.

What is the Best Solution for Employer Drug Testing?

We believe the best solution is to use rapid urine screens for pre-employment and random drug testing and use confirmations for any employee that has a positive result. You can also ask employees that admit to drug use to sign a waiver to save the cost of a confirmation.

This will keep drug testing costs low (our 12 panel drug tests are $2.70 per cup shipped when bought in bulk) while also having a very efficient and accurate drug testing policy. With a CLIA waived test almost any employee can conduct the test. By following on site drug testing guidelines you can eliminate most adulteration and reduce the cost of keeping your business drug free.



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What if My Drug Test Results Come Back Positive?

drug test results come back positive

You were given a drug test recently and when the results came back you were positive for one or more drugs. You may have suspected you would fail, or in rare cases it’s a total surprise. What should you expect and what should you do when your drug test results come back positive?

Don’t Freak Out When Your Drug Test Results Come Back Positive

A positive drug test is not the end of the world. The first thing to do is settle your mind. You don’t need additional stress and worrying will have no effect on the outcome.

Consequences are hardly ever as severe as people expect, but people have done many things they regret immediately after receiving bad news. The worst thing you can do is continue using drugs.

What are the consequences of Failing a Drug Test?

Depending on what your drug test was for consequences can range from nothing to prison time. In the vast majority of cases people overestimate the consequences of failing a drug test, and in other cases they know exactly what to expect.

Unless someone has firsthand experience or knows someone that has been through the exact process with very similar circumstances, they will rarely have a totally accurate idea of the consequences of failing a drug test. Here are some likely scenarios by case.


If you fail your probation drug test it will most likely be sent to a lab for confirmation giving you several more days to worry. The consequences of a failed drug test will be different depending on your original crime, your time on probation, the drugs you failed for and your probation officer’s own discretion.

In most cases someone that has done well for a while and has their first infraction will be referred to a drug counselor and may be asked to attend rehab after an assessment. For someone that has failed multiple tests however you could have your probation revoked. People that do go to jail for a failed probation drug test often get out sooner than expected.

Pre-Employment Testing

If you fail a drug test when applying for a job 99% of the time you will not be hired and that will be the end of it. Many employers have a statute about how long a failed drug test will affect hiring, so you may be able to re-apply in 6 months to 1 year.

Random Drug Testing at Work

Many employers do random drug testing to comply with federal guidelines and meet insurance requirements. For small businesses the result of a positive drug test will mostly be up to the discretion of the owner. Your work history and importance will likely play a big part in how it turns out.

Larger corporations almost always have a drug treatment policy where employees that have a positive drug screen are given the opportunity to attend treatment and accept terms of a more strenuous testing program to continue their employment. A violation of this program will usually result in termination.

Post-Accident Drug Test

Employers are required to do a post-accident drug test of all involved parties when an on-the-job accident occurs that causes serious injury or death. This is probably one of the most serious drug tests. You and your company could face lawsuits and even jail time for negligence or manslaughter.

If you drive a vehicle or work around dangerous equipment, consider this before taking drugs even outside of work.

Medical Patient

Healthcare facilities drug test patients for many reasons. The most common is when prescribing narcotics. These tests are to inform the doctor about any drugs you may take or addictions you may have and depending on your treatment you may get a prescription anyway. In most cases during a healthcare screening you need to show positive for any drugs you are prescribed and negative for all other drugs. Any other result is a good reason for your Doctor to withhold a prescription or even discharge you from care.

What to Do If Your Drug Test Comes Back Positive

If your drug test comes back positive the first question you need to ask yourself is why you failed the test. If you used drugs accept that it’s your fault and admit guilt; probation officers and employers are more likely to help if you are honest and they will know you’re lying when the confirmation comes back.

If you have not used drugs you should request a confirmation. Make a list of all the medications you have taken in the last month and a list of any unusual foods you may have consumed. Educate yourself about false positives on a drug test and stay confident that it will be worked out at the lab.

If someone was injured on the job, you should retain legal counsel and not answer any questions unless instructed to by your lawyer. You should get a quantitative blood screen as soon as possible to document the levels of any drugs in your system. You may be able to use this as evidence in court if your impairment was truly not the cause of the accident.

Immediately quit taking drugs. In many cases you will face suspension or other consequences until you can pass a drug test.

If you have a drug problem seek help. The longer you use drugs the harder it is to quit and there are many benefits to living a drug free life.

The consequences for trying to tamper with a drug test are usually more severe in the legal system and healthcare, and identical to failing in an employment setting. Never attempt to adulterate a test because it will negate any opportunity for leniency or forgiveness.

Dealing With Positive Drug Tests

I cannot stress enough that failing a drug test is not the end of the world and in most cases the consequences are never as dire as people expect.

For organizations and individuals giving drug tests I would like to remind you that everyone deserves respect and just because someone fails a drug test does not make them a bad person. They are likely under a lot of stress and you can really help their state of mind by being understanding. Please do not use drug testing as a tool for personal revenge.

For anyone taking a drug test I’d like to remind you that the person in charge of your test is just doing their job and following procedure. They do not want to see you fail a drug test and it causes them a lot of stress knowing that you may lose your job or suffer other consequences as part of their job.



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What is a False Negative on a Drug Test?

False Negative Drug Test Result

Most people are familiar with false positives on drug tests, but are unaware of false negatives. What is a false negative on a drug test, what can you do to prevent them and what should you do if you identify one?

What is a False Negative Drug Test?

A false negative is any time that under normal circumstances a drug test would be positive for an individual but for some reason results are negative. An example would be a patient that is prescribed Oxycodone that takes his medication consistently as prescribed, but has a negative drug test during his doctor visit.

In most cases this is caused by the patient either purposefully or accidentally altering their urine sample. The most common false negative drug test is due to water loading.

False Negatives From Water Loading & Adulteration

Water loading is the process where a person drinks an excessive amount of water prior to giving a sample. Urine that is clear with no yellow tint is usually indicative of water loading. You will need to perform separate adulterant tests for Creatinine, pH and protein levels to prove that a test has been diluted by a subject ingesting excessive amounts of water.


urine color drug test chart
This chart shows how shades of urine relate to dehydration. When analyzing drug test samples, some color is preferable because urine that is completely clear cannot be distinguished from water without further testing.


Without adulteration testing pure water will show negative on a drug test assay because the tests are only meant to detect the presence of a certain drug or metabolite in a substance, not to detect if the substance is a valid sample. Subjects can simply add water to their urine, but to fool a witness they will ingest an excessive amount of water to dilute the urine that comes from their own body.

There are several products available that claim to help users pass urine drug screens. These products range from nothing more than fortified tea that dilutes your urine to products that claim to seal in fat cells for several hours. Many of these products will speed up the timeframe which a person can pass a urine screen even if it’s for no more reason than they’ve diluted their urine.

Improper Drug Test Selection

A mistake made by organizations conducting drug tests is improper test selection. Every organization will have their own considerations when choosing a testing device, but some drug tests will not detect every illicit substance that people assume.

Semi-Synthetic Opiates

Many times a doctor prescribes their patient oxycodone or another semi-synthetic opiate, but uses a 5 panel drug test that only has a test for opiates. The doctor has seen positive tests for opiates from his patients that are prescribed oxycodone, but his new patient tests negative. One study found that oxycodone was detected in 12% of opiate immunoassay tests, and many other synthetic or semi-synthetic opiates also require a special test for accurate results. 


Most assays for benzodiazepines detect their presence in the urine by testing for nordiazepam and oxazepam, the main metabolites of most benzodiazepines. Agents that follow a different metabolic pathway, such as triazolam, alprazolam, clonazepam, and lorazepam, have poor cross-reactivity with the assay due to the absence of these metabolites and thus frequently produce false-negative results. Some doctors prescribe diazepam, oxazepam, and temazepam instead to reduce lab confirmations.

False Negatives From Very High Cutoff Levels

If your drug tests have high cutoff levels it is more likely for a user that has recently ingested drugs to produce a negative result.

The National Institute of Drug Abuse and the Substance Abuse and Mental Health Services Administration publish recommended cutoff levels for drug testing which most companies follow. Dozens of other federal agencies publish their own standard cutoffs (everyone from the Department of Transportation to the Nuclear Regulatory Commission) that are usually based off federal recommendations.

Even though the federal government publishes their own guidelines laboratories and manufacturers can create products that use whatever cutoff level they deem appropriate and the federal guidelines do change from time to time.

For example opiates and morphine have two widely used cutoff levels since the early 2000s because so many people were failing employment tests because the popularity of poppy seed muffins. The recommendation soared from 300ng/ml to 2000 ng/ml. The majority of tests will use this recommendation to stay compliant with as many federal regulations as possible, but the high sensitivity tests are still available.


Poppy Seed Muffin
Poppy seed muffins caused so many false positives in the 1990s that the NIDA introduced a new cutoff level for Opiates.


In practice there is no right answer. Some regions may have popular restaurants that sell poppy seed muffins, and some industries may have a high percentage of clients that anticipate testing and use gray-hat adulteration methods to get their levels under the cutoff.

Human Error

We advertise our drug tests as being 99% accurate, but in any situation that involves a human there is a possibility of introducing human error. A technician could mislabel tags, forget to confirm the temperauture on a sample or give a patient an opportunity to switch out a sample altogether.

Human error is even more likely in a laboratory where a technician has to prepare an assay, control variables, process and record information and interpret results. Never count out human error entirely and implement procedures that can help reduce the likelihood of human error.

Faulty Device

Since the consequences of a failed drug test can be so severe t here is a great deal of work and investment that goes into quality control for drug test devices. Still there are always some faulty tests or batches of tests that slip through.

If you have several tests in a row give unexpected results you should consider that the tests may be faulty. It’s very cheap and easy to use a 2nd drug test if a subject says that their results aren’t accurate.

Our drug test cups are designed to alert the user when there is a problem with the device itself. The control line can alert you to tampering, a faulty test and some forms of improper collection.


invalid drug test result
Any test that does not show a control line is invalid and can indicate anything from a faulty test to tampering.


Keep in mind that a 12 panel drug test is actually 12 individual tests; most of the time a faulty device means only one of the strips is faulty. A certain percentage of faulty tests is expected in this industry, which is why we offer a 100% satisfaction guarantee that covers any faulty devices and any additional tests you use to troubleshoot a possible faulty test.

Other Anomolies

There are times when all of the devices are functioning properly, everyone did everything they were supposed to do and a sample is valid in every way and still there is a false negative drug test result.

The Hook Effect

One rare cause which has been addressed by manufacturers in recent years is the “hook effect” where there is so much of a drug present in the urine that there are no more binding sites left on the antibody. This can cause a lower apparent level which can lead to a negative result if it’s below the cutoff level.

Drug Degradation

One benefit of using a drug test cup is that the receptacle is also the test. There is no lapse in time between collection and testing. In a busy medical office technicians may become distracted or intentionally multi task when working on test results.

When shipping to a lab it could be even more time between collection and testing. The time in transit and any time that the shipment sits in the lab without proper refrigeration is more time for the sample to naturally degrade.

Most metabolites are stable for the short periods common in drug testing, but others are not stable especially when subjected to temperature changes or extremely high temperatures.

One example is 6-monoacetylmorphine (6-MAM), a metabolite of heroin. In the body heroin is metabolized to 6-MAM, which then metabolizes to morphine.  6-MAM lacks stability, is subject to in vitro hydrolysis and also continues to metabolize into morphine even after the urine leaves the body. One study showed that within 7 days at room temperature a urine sample that was positive for 6-MAM had hydrolyzed completely into morphine.

Limiting False Negatives on Drug Tests

Understanding that a false negative is a possibility and the likely causes is the first step in stopping them. Collecting and storing data can be an important part of investigating unexpected or suspicious results.

With enough knowledge and proper analysis many drug test results that are contradictory to expectations can be reconciled and explained. Here are some other tactics you can use to limit the likelihood of false negatives in your drug testing program.

  • Institute procedures and policies to combat water loading and adulteration
  • Use a 12 panel drug test to cover many of the synthetic and semi-synthetic opiates
  • Understand the cutoff levels and detection times for the tests you use
  • Institute policies and procedures that decrease the likelihood of human error
  • Report faulty tests to the manufacturer or retailer



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What is a False Positive on a Drug Test?

False Positive drug test

When people fail drug tests they often claim that it was faulty or there is some mistake. In most cases this is a ruse and the individual is dirty, but false positives on drug tests are real and many innocent patients have failed a drug test only to be vindicated later on by a confirmation. So what exactly is a false positive on a drug test and when is it just another attempt at subverting drug test results?

What is a False Positive on a Drug Test?

A false positive is a drug test result that is not accurate due to another substance mimicking the target metabolite.

The majority of false positives are caused by medications, foods, and supplements that are well known to cause false readings on a drug test.

Some people have gotten a false positive from second hand marijuana smoke. The most common false positives are for benzodiazepines, amphetamine, methamphetamine, marijuana and opiates.

A presentation given at the American Psychiatric Association’s annual meeting in 2010 by a researcher at the VA Medical Center in Black Hills South Dakota, Dwight Smith,  5 to 10 percent of all drug tests result in false positives and 10 to 15 percent result in false negatives.

My anecdotal research at a healthcare facility where I tested hundreds of patients each month did not support these high numbers, but we did experience a 1 to 3 percent occurrence of false positives.


CBD products come in many varieties, some have had all traces of THC removed entirely and some have not.


Most studies show that second hand smoke from marijuana and crack cocaine do not cause false positives but there have been anecdotal cases. The growing popularity of CBD products and confusion about which products contain trace amounts of THC have cause some false positives.

Many drugs have multiple identified metabolites and different immunoassays and equipment use different technologies to bind antibodies. The regeants in multi-drug test cups are generally the most stable and prominent metabolites of each drug.

Some substances will cause a false positive on a specific test under specific circumstances, but will show as negative when retested for different metabolites or using different equipment.

Legitimate false positives are rare unless a patient is prescribed a drug that is well known for causing false positives.

What Should testing Programs Do About False Positives?

Always acquire a thorough list of all the patient’s prescription, over the counter and herbal medications prior to testing. Interview the patient to find out if they drink energy drinks or eat any products that are known to cause a false positive.

Discuss adherence to medications and instruct them about how much water to ingest prior to testing to keep from diluting a sample.

A good practice is to ask an individual that just failed a drug test if they are positive for the substance. Encourage an honest answer and let them know that lying about it will only damage their desired outcome. Many people will admit to a mistake.

Always send contested drug test results to a lab for confirmation. Let the individual know that their sample will be sent to a lab that can confirm exactly what substance triggered the positive result.


Lab Drug Testing Instrument
This Gas Chromatography / Mass Spectrometry instrument combines the two techniques to give the most accurate analysis of a urine sample. By Polimerek – Own work, CC BY-SA 4.0,


When you receive the results back schedule a consultation with the individual and give them another chance to admit to their drug use before revealing the lab results.

Many courts have started programs where criminals that are alcoholic are given home incarceration on non-violent charges if they install a phone that has a breathalyzer built in. Probationers and prisoners that sign up for these programs agree that even if a positive reading comes from using mouth wash that is doesn’t matter and they will be violated as an offence.

A lot of our customers send all positive tests to a lab for confirmation, but also make decisions for care and treatment based on the results of the instant drug test.

Always instruct your clients that false positives are treated as a failed test until a lab returns the confirmation results and it is their responsibility to educate themselves about substances that could possibly affect their test results.

Things That Can Cause a False Positive on a Drug Test

One study found adulteration from household cleaning products H202 and Joy detergent caused false positives for benzodiazepines and sodium bicarbonate caused extremely high pH levels.

One study found that gentle baby soaps Johnson &Johnson, CVS Nighttime Baby Bath, Aveeno Soothing Relief Creamy Wash, and J&J Bedtime Bath caused false positives for THC for infants being tested due to their mother’s suspected drug use.

Since drug testing is used so frequently in so many applications many organizations conduct studies about false positives. Still there are so many substances humans ingest and interact with that we couldn’t possibly identify them all.

Below is a list of medications and other substances that are known to cause false positives in urine drug screens. Some will often cause an inaccurate result while others almost never do.

Once a possible cross contamination is identified use multiple confirmation methods and research the history of that medication in causing false positives. Most of these medications were identified through scientific research, but a few are from anecdotal observations at medical facilities.

Marijuana (THC) False Positives

In a study conducted to find if second-hand marijuana smoke would cause a false positive 3 non-smokers were exposed to 8 marijuana smokers who smoked 32 joints in total in a 10×10×8-ft enclosed room. No samples from the nonsmokers exceeded the federal mandated threshold. However marijuana has increased in potency since this study.

The metabolite of THC is metabolite 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH). Even though excessive intake of several substances have caused a false positive for THC, the only drug that is likely to cause a false positive is Efavirenz (Sustiva). Other known false positives are very unlikely.

  • Ibuprofen (Study)
  • Hemp Seeds
  • Efavirenz (EFV, Sustiva)
  • Ibuprofen
  • Naproxen
  • Niflumic Acid
  • PPIs (Omeprazole)

Cocaine False Positives

In a study to find if being exposed freebase crack cocaine vapors would cause a false positive, 6 volunteers in an 8×8×7-ft enclosed room were exposed to 200 mg freebase cocaine vapor; none of their urine samples exceeded the federal threshold.

Individuals that work in a jobs such as law enforcement and medicine that handle cocaine are at risk for testing positive. Cocaine can be absorbed through the skin.

A study of crime lab technicians showed 33% of subjects tested positive after analyzing solid dosage forms of cocaine. Levels in two criminologists working with large amounts of cocaine in a small room were measured up to 278 ng/mL when wearing a face mask and gloves and up to 1,570 ng/mL when wearing gloves only.


Half Kilo Cocaine
Crime labs sometimes process vast amounts of cocaine. Samples are taken from several locations of a brick to confirm the composition and purity of the evidence.


In a study of physicians administering cocaine to a patients, one physician in the group not wearing gloves had a positive test with 53 ng/mL of the cocaine metabolite in his test eight hours following exposure. Results were negative in the group wearing gloves. Another physician in this study was asked to handle cocaine for two minutes and wait 15 minutes before hand washing every two hours. This physician had a positive test of 245 ng/mL 18 hours after exposure.

Many public surfaces have been shown to be contaminated with cocaine. An analysis of 234 banknotes from 18 different US cities found that 90% contained traces of cocaine. 85% of bills in Canada had traces of cocaine and 80% of bills from Brazil. They contained up to 2,350 micrograms.

Scientific studies have found no evidence that Lidocaine or norlidocaine can cause a false positive on standard cocaine tests, but there is anecdotal evidence it is possible.

  • Coca Tea

Opiates False Positives

In 1998, the federal government increased the threshold defining a positive screen for urine morphine and codeine from 300 to 2000 ng/mL to reduce spurious reports of opiate-positive tests from poppy seed consumption.

Synthetic and semi-synthetic opiates are sometimes detected in an opiate drug test, but sometimes are not. One study found that oxycodone was detected in 12% of opiate immunoassay tests.

Given this inconsistency separate tests have been developed for semi-synthetic opiates oxycodone, hydromorphone, oxymorphone, levorphanol, buprenorphine and synthetic opiates fentanyl, methadone, propoxyphene, meperidine, tramadol, pentazocine. The most common pharmaceutical opiates are included in some multi panel tests while others must be performed separate.


Poppy Seed Muffin
Poppy seed muffins caused so many false positives in the 1990s that the NIDA introduced a new cutoff level for Opiates.


  • Poppy Seeds
  • Codeine
  • Dextromethorphan (Robitussin, Delsym)
  • Dihydrocodeine
  • Diphenhydramine (Benadryl, Advil PM)
  • Levofloxacine
  • Ofloxacine
  • Naloxone
  • Pentazocine
  • Quetiapine
  • Rifampicin
  • Doxylamine
  • Fluoroquinolone

Methadone False Positives

  • Tapentadol
  • Verapamil
  • Cyamemazine
  • Creatinine
  • Doxylamine
  • Quetiapine (Seroquel)
  • Thioridazine
  • Diphenhydramine
  • Clomipramine
  • Chlorpromazine
  • Levomepromazine

Buprenorphine False Positives

  • Codeine
  • dihydrocodeine
  • Amisulpride and sulpiride

Benzodiazepines False Positives

  • Oxaprozin (Study)
  • Sertraline (Zoloft)
  • Efavirenz (EFV, Sustiva)

Amphetamine False Positives

  • Pseudoephedrine (Sudafed)
  • Phentermine (Adipex)
  • Dimethylamylamine (DMAA)
  • labetalol
  • Bupropion (Wellbuturin)
  • Chlorpromazine
  • Metformin (Glucophage)
  • Ofloxacin
  • Promethazine
  • Trazodone
  • Fluoxetine (Prozac)
  • Methylphenidate (Ritalin)
  • Vicks Inhaler

Methamphetamine False Positives

  • levomethamphetamine
  • Metformin (Glucophage)
  • Fluoxetine (Prozac)
  • Labetalol
  • Methylphenidate (Ritalin)
  • Vicks Inhaler

Tricyclic Antidepressants (TCA) False Positives

Tricyclic Antidepressants replaced PCP on many multi drug screens because so many TCAs cause a false positive for other drugs. Having the TCA strip on your multi-panel drug test can help identify cross-reactions with other drugs.

  • Seroquel (quetiapine fumarate)
  • Trileptal (oxcarbazepine)
  • Benadryl (diphenhydramine)
  • Flexeril (cyclobenzaprine)
  • Thioridazine
  • Thorazine (chlorpromazine)

Barbiturate False Positives

  • Ibuprofen
  • Naproxen

PCP False Positives

  • Venlafaxine
  • Tramadol
  • Dextromethorphan (Robitussin, Delsym)
  • Doxylamine

LSD False Positives

  • Ambroxol
  • Ergonovine
  • Lysergol
  • Amitriptyline (Amitril)
  • Diltiazem (Cardizem)
  • Fluoxetine (Prozac)
  • Labetalol
  • Methylphenidate (Ritalin)


Additional Sources:

False-Positive Interferences of Common Urine Drug Screen Immunoassays: A Review
Alec Saitman, Hyung-Doo Park, Robert L. Fitzgerald
Journal of Analytical Toxicology, Volume 38, Issue 7, September 2014, Pages 387–396

Analysis of the cocaine metabolite in the urine of patients and physicians during clinical use
Bruns AD, Zieske LA, Jacobs AJ.
Otolaryngol Head Neck Surg. 1994; 111: 722-6

Occupational exposure to cocaine involving crime lab personnel
16. Le SD, Taylor RW, Vidal D, Lovas JJ, Ting E. .
Journal of Forensic Science. 1992; 37(4): 959-68.


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Can Drug Tests Detect Gender?

Can a Drug Test Detect Gender

We’ve all heard the stories of a man bringing his wife’s urine to cheat on a drug test and when he asks the doctor about his results the doctor responds “well you’re clean on drugs, but did you know you were pregnant?”. Can drug tests detect gender, or is this an urban legend that is an entertainment trope?

Can drug tests detect gender?

This is actually a complicated question with many aspects. In the simplest terms a drug test itself cannot detect gender. A drug test only tests for the presence of specific metabolites associated with a specific drug.

Are you worried you may fail a drug test?
Are you worried you may fail a drug test?

Drug Test City drug tests are made to the same standards with the same cutoff levels as most drug tests used nationwide. Purchase our 12 panel drug test cups to ease your mind and know for sure if you would fail a drug test today.

However urine tests are widely available that detect hCG (human chorionic gonadotropin), a hormone that is produced by the placenta of pregnant women. Many of our clients have a need for testing women for pregnancy because the type of treatment and care changes for a patient that is pregnant. It is relatively cheap to add an hCG strip to testing.

hCG Pregnancy Test
A pregnancy test detects levels of hCG in a woman’s urine. The placenta starts to release hCG as early as 14 days after fertilization.

In cases where drug tests are sent to the lab a gas chromatography and mass spectrometry instrument breaks down the sample into all its components. For confirmations a lab technician will focus on the analyte associated with the positive test strip, but all of the compounds are identified. A high level of hCG would be recognized fairly quickly.

So it is true that drug testing would identify pregnancy in cases when providers test for pregnancy or samples are sent to a lab. The assays found in drug test cups and used in laboratory immunoassay tests do not detect hCG though.

What Are the Differences in Men and Women’s Urine

In the rare case a lab technician or medical review officer suspects a subject has used a urine sample from someone of the opposite sex the sample can be put through additional analysis to support their suspicions. Even though a drug test itself cannot determine gender, other tests can indicate gender.

The biggest differences in each sex’s urine are trace hormones, but there are indicators that may cause a lab technician to become suspicious and investigate further.


  • Women’s urine can contain hCG (the analyte used to detect pregnancies).
  • Women’s urine can be contaminated by blood during menstruation.


  • Men process alcohol differently. Higher concentrations of dehydrogenaze are present after consuming alcohol.
  • Men have higher muscle mass which can increase creatinine levels.
  • Male samples can contain traces of sperm or pre ejaculate, however females can too for 8-12 hours after sex.

Foreign matter such as blood and semen are good indicators of gender, but are far from definite because men can have blood in their urine and women can have male semen in their urine after sex.

The easiest hormone to identify a person’s gender in urine is testosterone. Men produce less testosterone as they age, but will always excrete significantly more testosterone in their urine. Marijuana has been shown to suppress the production and secretion of testosterone and other androgens.  A study conducted by the Worcester Foundation for Experimental biology found that men excrete 28-250 μg of testosterone in their urine, while women excrete 2.4-8μg.

Testosterone Levels in Urine

Sex / AgeAVG Testosterone Levels
Male 18-28171 μg (range 65–250)
Male 30-3589 μg (range 45–150)
Male 42-5581 μg (range 28–159)
Female 23-376 μg (range 2.4–8)

Can Drug Blood & Hair Drug Tests Detect Gender?

It is almost impossible to adulterate or substitute hair or blood samples during a drug test because a subject has to physically present themselves to have samples taken. A technician will confirm the identity of the subject at the time of sample donation. Any anomalies that indicated a different gender would be investigated as a health issue instead of possible tampering.

However, the same hormones that are present in urine are present in a person’s blood, and DNA from human hair can be used to determine a person’s gender.

Hair samples can give an indication of gender simply by the length and treatment when examined under a microscope, but nuclear or mitochondrial DNA would be needed to determine gender with a hair sample definitely.

Considerations When Testing Different Genders

Even though the basic mechanisms of how a drug test works is the same whether you are testing a male or female, there are some differences you may want to account for. For example women process alcohol slower than men. It would be easier for a female to have some drinks at night and still have alcohol passing through their system the next morning.

Another consideration is that women have a much higher body fat percentage than men. A healthy middle aged male has a body fat percentage of 20% while a healthy female of the same age has a body fat percentage of 30%. Drugs or metabolites that bind to fatty tissues can be detected longer in an individual with a higher body fat content.

GenderBody TypeBF % Age 20-39BF % Age 40-59BF % Age 60-79

This doesn’t mean that a woman that you should alter results for females, but there are many instances when this knowledge is useful. For example after a failed drug test you can expect women to have a slightly longer detection time for drugs that have an affinity for fatty tissue. It can help with scheduling retests, confirming patient statements, and advising clients about detection times.

Will You Get Caught if You Use Urine From the Opposite Sex to Cheat a Drug Test?

Using urine from the opposite sex to pass a drug test will go unnoticed in the vast majority of drug screens because assays only detect the metabolite they are designed for. A male using a pregnant female’s urine would increase the likelihood of being caught because of the hCG content.

However, you are much more likely to be caught  substituting urine by a witness during screening, a cold temperature strip, suspicion from staff, or a number of other discrepancies that are present when you substitute someone else’s urine for a sample.

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Which Drug Test Do Most Probation Offices Use?

Drug Test at probation office

Drug testing parolees and probationers is one of the most complex and specialized instances of drug testing. The consequences are high and the subjects are very clever when it comes to tampering. Probationer officers and parolees alike often want to know which drug test probation offices use.

Which drug tests do most probation offices use?

The 12 Panel Clia Waived drug test is by far the most common test used by probation offices across the country. A 12 panel drug test covers all of the well known illegal drugs such as cocaine, marijuana, heroin and ecstasy as well as pharmaceuticals like opiate painkillers, Xanax, valium and buprenorphine.

Users are always finding new drugs that they can take that won’t show up on a drug test, but a 12 panel drug test pretty much covers the basics for probation office use.

Neurontin 800 mg
Neurontin was recently added as a scheduled narcotic after probation officers found their clients were taking Neurontin because it wasn’t on their drug test.

Across the United States however testing varies. Probation officers choose tests based on the drug use in their area. Almost all probation offices use instant drug test dip cards or cups, but some use 5 panels and some use 12 panels.

12 Panel Drug Tests - Lowest Price Online
12 Panel Drug Tests – Lowest Price Online

Drug Test City drug tests are made to the same standards with the same cutoff levels as most drug tests used nationwide. Purchase our 12 panel cups to see for sure what is on a 12 panel drug test .

For instance one probation office surveyed in North Carolina used 5 panel tests, but also had alcohol and benzodiazepine tests to use for probationers that used those drugs and to randomly check others. A probation office in Michigan used 12 panel tests but also used an ETG (alcohol) test.

Why 12 Panel Drug Tests?

The main reason probation offices would choose a 12 panel instant test is because it’s the most drugs you can test for in a single device and still have it CLIA waived. A CLIA waived test is important because it takes minimal instruction to use and officers do not need special training.

It is important for probation offices to use instant drug tests because they do a high volume of testing, it is much cheaper and it also allows officers to have immediate results. Positive test results will always be confirmed at a lab, and in most cases your probation officer will wait until those results come back to pursue any punishment.

12 Panel Drug Test Cup Strips shown
Probation offices can purchase Drug Test City 12 Panel Drug Test Cups for $2.70, which saves tens of thousands of dollars annually over a drug testing lab.

Drug Test Cups are preferred because the price difference is negligible and they’re much more sanitary than using dip cards.

During the last decade probation officers used 5 panel tests that would identify the use of most popular illicit drugs including heroin, marijuana cocaine and methamphetamine. As areas started to see more prescription drug abuse they started to expand to cover the most widely abused prescription medications.

In some regions it is fairly easy to get a prescription to cover this type of drug use, which slowed down agencies from adopting more comprehensive drug tests even more.

Probation Drug Testing Changes on a Regional Level

One probationer that was released from his probation in 2007 said, “I was caught in Minnesota with Oxycontin and charged with felony possession. I was offered a plea bargain that would drop the felony to a misdemeanor in exchange for 1 year on probation, they said I was the first person to ever be caught with pain pills crushed up. Once I checked in at my probation office I noticed they only used a 3 panel drug test, so I continued using prescription painkillers the entire probation”.

States like West Virginia saw an early rise in prescription drug abuse and changed their drug testing programs to reflect that. From 1999 to 2004 deaths from unintentional drug poisoning increased 68% nationwide, while West Virginia experienced the Nation’s largest increase at 550%. West Virginia probation offices were purchasing panels for Oxycodone and other prescription medications as early as 2001.

As prescription drug abuse has increased across the country so has testing for those substances. In 2020 the majority of probation offices are using 12 panel drug tests that are comprehensive, but there are still offices that focus primarily on illicit drugs that have no medical use.

The Future of Probation Drug Testing

Probation officers change with the landscape. Many are already using additional panels to test for alcohol and fentanyl, and some probation offices have started random testing for Gabapentin (Neurontin) because probationers often turn to drugs that aren’t as well known to get high without risking arrest. Other popular replacement drugs are Tramadol, Kratom and designer drugs like spice, K2, Flakka or bath salts.

Most drug tests will include fentanyl after the FDA starts issuing CLIA waivers for those panels. Most 12 panel drug tests have removed PCP and replaced it with Tricyclic Antidepressants in the past few years.

It is a constant game of cat and mouse between probation officers and probationers trying to cheat the system. The only thing for certain is that probation officers will continue to change up and surprise probationers and the only surefire way to keep from getting your probation revoked is to obey the law and practice abstinence from drug use during your sentence.

If you’re a probation officer or probationer we’d love to hear about your drug testing program and which tests you use! Contact us and let us know.