Wed. Apr 24th, 2024

Drug tests are of great importance, and they are mostly used for different purposes, and one of the major issues of concern is the correctness of the results that are gotten from these tests. A common thing among most people today, especially professional athletes, is to use false positive as a way to defend themselves after the results of a drug test is released. In general, it’s completely normal to get an unexpected result after a drug test, and this can happen for many reasons. 

When playing sports, applying for a job, or taking part in a drug rehabilitation program, you might be affected by a false positive result, and this could be due to the fact that you are taking another medication that’s sensitive to the testing method that’s used. There are several drugs, over-the-counter and prescription that can interfere with drug results and give a false positive result. 

In this article prepared in collaboration with, we have provided an overview of the drugs that can give false positives, so read on. 

What is a False Positive?

Before we go into the different drugs that can give a false positive, let us look at what is a false positive. Drug screen tests are mostly used in checking for the presence of an illicit drug, as well as prescription medications that are prone to misuse and abuse. A false positive is a term used in describing cases where these tests detect the presence of the substance in the body, even without actually taking them. There are different foods, drugs, and other substances that can cause false positives. 

The most common drugs that are tested for include cocaine, amphetamines, phencyclidine, opiates (codeine, morphine, opium, and heroin), and THC (marijuana). The tests may also be performed to check for opioids like hydrocodone and oxycodone, MDMA (ecstasy), steroids, LSD, Methadone, Benzodiazepines, and Barbiturates. 

Drugs that can Cause False Positives

If you have taken any of the medications below, there’s a great chance you’ll get a false positive test result. It’s generally advisable to work with a healthcare provider to help you ascertain whether you’ll get a false positive due to any of the following drugs below. In some cases, it’s best to get a confirmatory test or a repeat test. 

Here are the drugs that can cause false positives:

  • Dextromethorphan

This is the main ingredient in Delsym, Robitussin, and so many other over-the-counter cough medications and suppressants. If you’ve used any medication that contains dextromethorphan in it, you’re likely to get a false positive when you screen for phencyclidine and opiates. 

  • Diltiazem

This is a drug that’s used in managing hypertension, and it works by reducing heart rate in people with atrial fibrillation. If you’ve taken diltiazem, you’ll get a false positive result when screened for LSD. 

  • Diphenhydramine

This is the active ingredient in Benadryl, and diphenhydramine is an antihistamine. It is also a drug that is found in several medications for allergy, and examples included Advil PM and Tylenol PM. If you’ve recently taken any medication containing diphenhydramine, your drug test result will show positive for phencyclidine, methadone, or opiates. 

  • Metformin

This is a very common medication that is used in managing diabetes and can cause a drug test to give a false positive, especially if the test is for methamphetamine or amphetamine. 

  1. Pseudoephedrine

This is an effective drug that’s used for nasal congestion. Like metformin, it can also cause false positives in drug tests to detect the presence of methamphetamine or amphetamine. 

  • Labetalol

This is both beta- and an alpha-blocking agent that also effectively controls blood pressure levels. People taking labetalol could get a false positive when they test for LSD, methamphetamine, or amphetamine. 

  • Methylphenidate

This is a drug that’s used in managing and treating ADHD, and a well-known brand of this drug is Ritalin. It is also known to cause false positives in drug tests for LSD, amphetamine, or methamphetamine. 

  • Doxylamine

This is the active ingredient that’s found in Unisom and so many other over-the-counter drugs for sleeping disorders. Doxylamine also has the tendency to cause false positive in drug tests for phencyclidine or methadone. 

  • Tramadol

This is a drug for moderate to severe pain management, and it also causes false positive in tests for phencyclidine or opiates, especially if you’ve taken it recently. 

  • Phentermine

This is the active ingredient in Adipex-P, and it’s a drug that’s mostly used in the United States for weight loss. The drug works by increasing the release of neurotransmitters responsible for the stimulation of metabolism and suppression of appetite. The drug can cause a false positive in a drug test for amphetamines and methamphetamines. 

  • NSAIDs

NSAIDs like naproxen and ibuprofen are among the most commonly used NSAIDs, and they are used in managing different pain conditions. The drugs can alter urine tests and give false positive in tests for THC or barbiturates. Ibuprofen can also give a false positive for phencyclidine. 

Another NSAD is Oxaprozin, which is also used in treating pain due to arthritis. This can also give a false positive for drug tests for benzodiazepines. 

  • Antidepressants

These are drugs used in managing depression, and examples include Venlafaxine, Quetiapine, Sertraline, Trazodone, Amitriptyline, and Bupropion. There are a lot of other antidepressants. These drugs can cause false positives drugs test for different illicit drugs. Taking these drugs before a drug test can give positive for LSD, amphetamine, methamphetamine, methadone, phencyclidine, and opiates. 

  • Proton Pump Inhibitors (PPIs)

PPIs like pantoprazole, esomeprazole, and omeprazole are mostly used in treating heartburn symptoms and gastroesophageal reflux disease. Taking these drugs before a drug test can give a false positive to THC. 

  • Quinolone Antibiotics

Examples of these antibiotics include ofloxacin and levofloxacin. They are mostly used in managing urinary tract infections, sinus infections, pneumonia, and other types of infections. The drugs can cause false positives in different opioid tests. They can also show false positives in tests to detect methamphetamine and amphetamine. 

These are the most common drugs that can cause a false positive in different drug tests.

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