Tag Archives: positive drug test

Positive Drug Test List of Causes: Medications and Food

How to dispute a false positive drug test, foods that cause false positive drug tests, medications that cause false positive drug tests, positive drug tests, what can cause a false positive for THC, false positive for PCP.

More and more people are required to undergo drug testing to obtain employment. It is a shock — and often an embarrassment — for someone who abstains from illegal drug use to discover that he or she has had a positive drug test. How did this happen? Most likely, the person recently took one of several medications that cause false positive drug test results. There are even certain foods that cause a false positive drug test.

What can a job candidate, or anyone else who needs to pass a drug screen, do to avoid triggering a false positive drug test? First, it is important to learn what medications and foods to avoid during the days leading up to a drug screen. It is also good to know how to dispute a false positive drug test.


Most Drug Tests Look for Evidence of Illicit Drug Use


Job candidates who are told they need to take a drug test should be aware that some prescription and over-the-counter (OTC) medications can alter drug test results. 

Most employment drug screening panels look for evidence of opiates, hallucinogenics, methamphetamines, PCP, or THC, the active ingredient in marijuana. And yet there are legitimate medications that can cause a false positive drug test for several medications.


Medical Marijuana and THC in Drug Screen

Probably the biggest concern is understanding what can cause false-positive results for THC. In part, that’s because edible medical marijuana has THC in amounts sufficient to show up on a drug screen. People who regularly take naproxen (found in ibuprofen) can also test positive for THC. These are common, over-the-counter drugs that are also prescribed in larger doses to control pain from surgery, childbirth, and injuries.


Many people diagnosed with GERD (gastroesophageal reflux disease) are prescribed medication from a class of drugs called proton pump inhibitors (PPIs). Not all patients need to take a PPI daily, but those who do can test positive for THC.


Common Pain, Sleep, and Cough Medications Might Trigger a False Positive for PCP


PCP,  or phencyclidine, is a strong hallucinogenic, or disassociative drug also known as angel dust. Its abuse became a serious problem in the 1970s and 1980s. Today, it is commonly laced into other street drugs including as much as 25% of non-medical marijuana. 

Several OTC pain relief medications and at least one prescription pain reliever are known to cause a false positive for PCP. Other medications that also trigger false positives include popular cough and sleep medications.

SNRI (serotonin-norepinephrine reuptake inhibitor) medications can return a false positive for PCP. These are prescription drugs that treat major depression, attention deficit hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), anxiety, and a few other conditions. 

  • Ibuprofen (Motrin, Advil) and naproxen (Aleve)
  • Diphenhydramine, found in Benadryl and sleep medications like Tylenol PM and Advil PM
  • Tramadol, a prescription-only pain reliever
  • Venlafaxine, found in SNRIs antidepressants 
  • Dextromethorphan, the active ingredient in OTC cough syrups including Robitussin and Delsym
  • Doxylamine, found in OTC sleep medications like Unisom

Other Common Medications That Cause False Positive Drug Test Results


Several other medications can cause false-positive results for opiates, hallucinogenics, amphetamines, and methamphetamines. Here are a few of them:

  • Diphenhydramine (Benadryl) – methadone and PCP
  • Fluoxetine (Prozac) – amphetamine, methamphetamine, and LSD
  • Metformin (Glucophage) – amphetamine or methamphetamine.
  • Methylphenidate (Ritalin) – amphetamine, methamphetamine, and LSD
  • Pseudoephedrine (Sudafed) – amphetamine and methamphetamine
  • Sertraline (Zoloft) – benzodiazepines and LSD

Novocaine and Lidocaine will not cause a false positive test for cocaine. 

Foods that Cause False Positive Drug Test Results


A few foods are known to throw off drug test results, the most famous being poppy seeds baked into bagels and pastries. Many opiates are derived from poppy seeds including morphine and codeine.

Poppy seeds used in baked products are usually processed enough to avert any drug issue, although eating enough of them might cause a false-positive result. Raw seeds are generally inedible to most people. Quinine in tonic water is low enough that it is safe to be consumed in small amounts. But a drug test that detects high levels of it might lead to suspicion of opiate abuse because quinine is often used to cut heroin.

How to Dispute a False Positive Drug Test


Anyone who takes a drug test and is surprised by a positive result should first review any medications taken in the days before the test. It may be possible that something was omitted from the disclosure form.

Try to remember details about how the test was handled.

  • Could a specimen have been contaminated? 
  • Were staff administering the test and handling specimens wearing fresh clinical gloves? 
  • Did anyone appear ill? Coughing or sneezing around a specimen can contaminate it.
  • Was the facility clean? 
  • Was the test subject allowed to review the identification label attached to the specimen?

Some companies will allow strong candidates to retake a drug test. The best way to contest false-positive results is to reach out to your pharmacist and ask if prescription drugs and OTC medications you take on a regular basis can cause a positive drug test result. Ask if the pharmacist can provide written documentation to this effect and bring a copy to the test site. 

Remember, 15% of all drug tests return false-positive results. You aren’t alone in questioning a test’s accuracy. 

ScientiaDx partners with healthcare practitioners to improve the quality of patient care through drug testing. Medication monitoring can help identify possible illicit drug use and medication misuse. Reach out to our team to learn more about the services we provide.