What Can Cause a False Positive Drug Test? How to Prevent It?

Have you ever been asked to take a drug test? Maybe this situation has caught you off guard, but this is a standard procedure in the corporate world. The screening is required in a private and government sector, for health care workers, students, athletes, after vehicle, or workplace accident, and so on.

Even though these tests are quite common, people often have questions about false-positive results. However, if you are subjected to a drug screening, make sure to take the secondary confirmation testing on any affirmative results received. Otherwise, the false positive drug test might have severe consequences on your life, such as termination from a job and risk of a prison sentence.

So, what does this mean? Basically, the results show you are positive on the opioids you didn’t take. Now, you must be wondering how’s that possible. Well, based on numerous studies, nearly 10% of total cases are false positives, which is a shocking result.

But, let’s see how it happens and what can you do to avoid this unpleasant situation.

A false positive drug test can significantly impact an individual’s life in many aspects. For that reason, the accuracy should be taken quite seriously because it can jeopardize your career, work, and education.

In most cases, companies or public officials use panel tests due to their convenience. They contain antibodies which react and change color in the presence of opioids, or their metabolites. These type of tests work in the same way as the pregnancy ones. However, they only detect pregnancy-related hormones.

Panels are quick, easy to conduct, and useful, but, unfortunately, they are subject to errors. It means they pick up a substance that isn’t present in a sample. This usually occurs when the substance is chemically similar to the target compound.

These so-called imposters can be products of medications, food, and supplements. Even though the companies which manufacture panel tests try to minimize the fake positives, the growing number of prescription drugs makes it nearly impossible to reduce the results.

If you ever find yourself in a similar situation, make sure to schedule an additional screening, to avoid loss of employment and even jail.

What Can Cause a False Positive on a Drug Test?

As we already mentioned, these results are often caused by substances similar to a drug. However, they don’t have the same effect on the human body. The analysis detects foreign compounds in your bloodstream, saliva, or hair, and treats it as an opioid.

For example, if you have been sick in the last couple of weeks, you took some over the counter medicine, the results may show forbidden substances in your body. Therefore, you will be marked as a drug user on an opioid screening.

Common Classes of Drugs and Medications

The fake positives have been mostly reported in the following drug classes:
• Antibiotics
• Antihistamines
• Antipsychotics
• Antidepressants
• Analgesics
• Specific OTC products
• Decongestants
If you have been using medicines from this list, make sure to outline it, before you undergo the examination.

Tested Substance Categories

The urine test is the most common type, but other screenings such as saliva, blood, and hair are becoming popular. Based on the Federal workplace guidelines, the tested substances include five different categories:
• Marijuana/ THC/ Cannabinoids
• Cocaine
• Amphetamines/ methamphetamine
• Phencyclidine
• Heroin

Additional classes may include:

• Artificially manufactured drugs – ecstasy, salts, bath, or spice
• Alcohol
• Benzodiazepines – Xanax and valium
• Prescription medicines – methadone, hydrocodone, oxycodone

Medications That Cause False Positive

Medications That Cause False Positive

In this article, we will fully disclose a false positive drug test list, which is reported to lead to fake results.

Bupropion (Wellbutrin)

Bupropion is an antidepressant commonly used to treat severe cases of depressive disorders and seasonal affective disorders, as well as withdrawal effects. However, bupropion is closely connected to false positive to meth or methamphetamine and can cause you to fail your drug test results.


Dextromethorphan is applied when a patient suffers from a cough. It affects the signals in the brain, which trigger cough reflex. Since this medicine is available over-the-counter, it is often linked to a false positive drug test for opiates, as well as for PCP.

Diphenhydramine (Benadryl)

Diphenhydramine reduces natural histamine in the human body. Considering that histamine causes symptoms of runny nose, sneezing, watery eyes, and itching this drug is used to treat an allergy or cold symptoms.
Unfortunately, Benadryl can mess with your drug test results. Therefore, you must be careful with its use.

Ibuprofen and naproxen

Ibuprofen is a widely applied medicine in the U.S. However; based on some research; it can cause a fake positive for barbiturates. On the other hand, one study reported that chronic use of naproxen or ibuprofen is not regularly associated with errors which occur during the opioid screening.


People who are struggling with weight or are in some kind of exercise program take metformin usually. Additionally, when combined with other medications, metformin can reduce high blood sugar.

Unfortunately, in some cases, it has been found that this drug leads to false positive for meth or methamphetamine.


Labetalol is used to treat high blood pressure and often administered as an injection. It is given directly into a vein or as an infusion.

This drug can temper with the opioid screening, and show that person has used methamphetamine or meth, even though he or she didn’t.


Sertraline falls into a group of antidepressants which affect chemicals in the brain that appear to be unbalanced. People who suffer from panic attacks, depression, obsessive-compulsive disorder, and anxiety take sertraline.

However, it can lead to fake positive results, so make sure to take additional testing if they turn out to be.  

Tramadol (Ultram)

Tramadol has similar chemical substances like opioids, and it’s used to treat severe pain in adults. This is not a common painkiller, and it shouldn’t be treated as one.

However, some cases reported tramadol false positive drug test results, which is to be expected, considering its chemical structure.

Ranitidine (Zantac)

Ranitidine belongs to a group of medicines which are called histamine-2 blockers. It reduces stomach acids and improves digestion. Additionally, ranitidine can prevent ulcer and treat stomach issues.

But, can ranitidine cause a false positive drug test? It can. Due to its compounds, some test subjects reported irregularities.


Novocain is an anesthetic which causes numbness of the skin and mucous membranes. It is injected during the surgery and often used in medical and dental procedures.

But, Novocain has a substance called benzoylecgonine, which leads to benzoylecgonine false positive.

Diet Pills

Patients suffering from obesity tend to consume diet pills. They are often considered as a medical treatment, usually combined with low fat and low-calorie food.

However, some substances inside diet pills may cause irregularities when testing for LSD, meth, or amphetamine.

Sleep Aids

Usually, Advil PM or Tylenol are most common sleep aids. But, if you have taken diphenhydramine, which is a component found in these drugs, then drug test can show traces of methadone in your body.

Ephedrine Nasal Inhaler

Considering ephedrine nasal inhaler contains ephedrine or phenylpropanolamine, it can lead lab technician to believe you have used amphetamines. However, that’s not always the case.

Foods and Herbs That Cause False Positive

Foods and Herbs That Cause False Positive

Poppy Seeds

Pastries, bagels, and rolls often have poppy seeds sprinkled on top. However, they have been used as a defense against irregularities found in urine examination.

It’s a well-known fact that poppy seeds do contain a certain amount of opiates, mostly codeine and morphine. But, the content depends on processing and source of the seed.

Based on the study, which was published in the Journal of Analytical Toxicology, poppy seeds can lead to fake positive for morphine, as well as other opiates. On the other hand, as we already mentioned, it all comes down to quantity.

For that reason, the federal authorities raised the required morphine concentration from 300 to 2,000 ng/mL, due to a large number of irregular test results.

Coca Tea

Coca is a widely spread plant in Peru and Bolivia. Chewing leaves or drinking tea will offer you an energy boost, and many believe it helps with altitude sickness.

But, before you start sipping coca team, be aware it can cause a false positive for cocaine. If by any chance you have an upcoming drug screening, then make sure to avoid this tea or coca leaves.

Many studies have confirmed that just one cup of coca tea can leave cocaine for 36 hours in the human body, which is a significant risk to take.

Hemp Oil and Food Products

Hemp oil is a common ingredient in the food industry. We use the cannabis sativa plant to manufacture hemp oil, but it contains THC which is known to cause a “high” effect.

However, cannabis also features chemical compound CBD, which has numerous medical benefits without causing intoxication. Now, you must be wondering what can cause a false positive for thc? Well, some products that contain hemp oil may lead to fake results.

Vitamin B Supplements

Some group of vitamins and supplements, specifically B2, or Riboflavin, is made with hemp seed oil. It’s what can cause a false positive drug test for thc. Hemp contains traces of THC, which is a psychoactive component of marijuana.

We all know that weed is part of standard drug screenings, so you must be careful when taking these vitamins.

Snack Bars

You must think it’s weird that a regular snack bar can cause you to fail your opioid test. But it’s true. Scientists have discovered that KIND brand granola bar has hemp seeds.

This ingredient contains lower traces of tetrahydrocannabinol. Even though KIND granola can add extra protein to your diet, it can also expose your body to irregular test results.

So, make sure to read the ingredient list before you decide to eat similar snacks.

Tonic Water

You must be surprised to hear that tonic water can cause you to fail your drug screening. It contains traces of quinine, which is a medicine used to treat malaria. In some cases, quinine is combined with street drugs, which can lead authorities to suspect illegal actions.

A 1989 study confirmed that tonic water could generate a false positive for opiates.

Passive Marijuana Smoke

In extreme cases, secondhand marijuana smoke can cause irregularities in a drug test. However, that’s not always something you should be afraid of or avoid people who smoke weed.

For example, based on a study conducted in 2015, six people smoked marijuana in a sealed room, while six non-smokers sat next to them. The experiment lasted for one hour, and several non-smokers were tested positive for pot.

The closed space, proximity, and amount of smoke are what can cause a false positive for thc. In this particular case, the test subjects had a concentration of nearly 50 nanograms per millimeter. These results show that extreme secondhand cannabis exposure could temper with your upcoming screening.

On the other hand, the researchers also noted that these positive tests in real life are scarce. You need to spend hours in a closed chamber to suffer from passive marijuana smoke.

Passive Marijuana Smoke

Factors That May Cause Fake Positives

There are a couple of things which can affect the approaching opioid screening:
• The time of the test
• The type of detection technique, as well as the sensitivity
• Whether there is or not metabolic products of the actual drug

How to Prevent It?

Usually, it’s only people who consume drugs have to worry about screening results. On the other hand, individuals who stay away can relax, knowing there is no way for tests to come back positive. Right?

However, what if you are 100% sure that you didn’t take drugs, but your test results show otherwise. Here are a few things that might mess up with your screening:

  • Over the counter medication – when you’re sick, go see a doctor, and don’t act like one. Countless medicines, nearly 250 of them, contain a chemical ingredient which may cause a fake positive urine drug screen.
  • Limit a specific food and drink intake – as you already know particular foods such as poppy seeds, or coca tea can make a mess in your body. So, you better avoid them if you have an upcoming opioid examination.
  • Check your blood sugar level – diabetes, or kidney, and liver disease can lead to a fake positive.

False Negatives

This is probably what the majority of marijuana users want to hear! A false negative can happen, but it means that someone deliberately altered the results.

Nowadays, there is a lot of speculation online on how to pass any drug test. However, on our website, you can find plenty of articles dedicated to this subject, and they all have a high success rate.

Due to many alterations, lab technician, and laboratories have tightened the rule, so now it’s nearly impossible to tamper with samples. But, with the appropriate method, you can beat even the most challening screening.


Can Energy Drinks Cause a False Positive?

If you are a fan of Monster brand energy drink, then you might test positive on drugs. It happens that this drink contains Riboflavin, which is a form of vitamin B. As we already explained, specific vitamins and supplements can cause issues with opioid screening.

What Happens If I Fail a Drug Test While Pregnant?

A urine test on pregnant women can produce a surprisingly high rate of fake positives, especially of opiates and methamphetamines. On the other hand, the baby’s first stool is used to determine whether the mother used drugs or not in the past couple of months.

How to Dispute a False Positive?

There aren’t not a lot of things you can do. But, with the help of a lawyer, you can always request the second screening, to dispute the results.


A false positive drug screening can change your life in a matter of seconds. You can lose your job, face criminal charges, and even end up in jail.

However, before you start panicking and do something reckless, review your previous actions and ask yourself how did you get in content with drugs.

Maybe you got sick, and you took the wrong medicine, or perhaps you had your favorite snack bar, without realizing it contains “suspicious” ingredients?

Whatever the case is, make sure to ask for additional tests, and try to determine factors which led you to have fake positive. Remember, it’s not the end of the world, even though it might seem like that.

Use all recourse to prove your innocence and to get back to normal life.

Natural Revolution