Can You Get a False Positive Drug Test?

Most individuals will have gone through a drug test at least once in their lifetime. Drug testing is often done when applying for employment, especially for positions that may involve federal transportation, airline industries and pilots, bus drivers, trucker drivers, railways, hospitals, and other workplaces where public safety is of the utmost importance.

However, besides just for safety, workplace drug testing is now standard in general for many U.S. employers to lessen the impact of drug abuse, safety concerns, and low productivity in the workplace.

Can You Get a False Positive Drug Test?

Is it possible to get a false positive on a drug test?

Yes, you can get a false positive on a drug test. A false positive occurs when a drug test indicates the presence of a drug when the person has not actually used that drug. Several factors can contribute to false positives, including certain medications, foods, and medical conditions. Here are some common causes of false positives:


  1. Over-the-Counter Medications: Some antihistamines, decongestants, and nonsteroidal anti-inflammatory drugs (NSAIDs) can cause false positives.
  2. Prescription Medications: Certain antibiotics, antidepressants, and medications for mental health conditions can lead to false positives.
  3. Weight Loss Medications: Some weight loss pills contain ingredients that might cause a false positive.

Foods and Supplements:

  1. Poppy Seeds: Consuming poppy seeds can result in a false positive for opioids.
  2. Dietary Supplements: Certain supplements, especially those that are not well-regulated, may contain substances that cause false positives.

Medical Conditions:

  1. Liver Disease: Some liver conditions can affect metabolism and cause substances to appear in the urine that might be misinterpreted as drugs.
  2. Diabetes: High levels of ketones in individuals with uncontrolled diabetes can sometimes cause a false positive for substances like alcohol or amphetamines.

Lab Errors:

  1. Sample Contamination: Contaminants in the sample can lead to incorrect results.
  2. Cross-Reactivity: Some drug tests are not specific enough and can cross-react with other substances that have a similar chemical structure.

Prevention and Mitigation:

  1. Inform the Tester: Always inform the testing agency about any medications, supplements, or foods you have recently consumed.
  2. Confirmatory Testing: If you receive a positive result, ask for a confirmatory test, such as gas chromatography-mass spectrometry (GC-MS), which is more accurate and specific.
  3. Follow-Up: Discuss any unexpected positive results with your healthcare provider to explore potential causes and next steps.

False positives on drug tests can occur due to various factors. It’s important to communicate openly with the testing agency and seek confirmatory testing if necessary.

How Does Drug Testing Work?

Drug testing is the evaluation of a urine, blood, or another type of biological sample to determine if the person has been using any drugs against that workplace’s policy or determine if there may be a situation to be aware of. Many circumstances may require drug testing, which often includes:

  • Pre-employment drug screening test or random, work-related drug testing to identify on-the-job drug abuse.
  • College or professional athletic drug testing.
  • Post-accident drug testing is a vehicular or on-the-job accident involving human error and casualties or property damage.
  • Safety-related drug testing – if an employee’s job could lead to safety issues if the judgment or physical ability were impaired.

Prescription drug abuse is a severe problem in the U.S. As reported by NIDA; the Surgeon General states that alcohol and drug abuse, including tobacco, costs the economy over $740 billion per year. Costs are related to crime, lost work productivity, and health care.

We hear “false positive” as a defense from professional athletes or repeated drug users all the time when it comes to drug screens, but unexpected results on drug tests do happen.

What is a False Positive Drug Test?

A drug screen tests for the presence of certain illegal drugs and commonly abused prescription medications. A false positive means that the test has detected the presence of these substances in your body when you haven’t taken them.

You could be affected by a false positive at any time in your life, whether you’re applying for a job, playing sports, or participating in a drug rehabilitation program. Here are several common medications, prescription and over-the-counter, that can lead to a false-positive result on a drug screen.

Drugs That Can Cause False Positives

If you’ve taken one of these medications and had what you believe is a false positive test, speak to the employer, explain the issue, and speak with your healthcare provider to see if you can stop taking the medication or cut back on it. Then ask to repeat the test to confirm.


Dextromethorphan is an active ingredient in Robitussin, Delsym, and other over-the-counter cough suppressants. If you’ve taken medication with dextromethorphan in it, your drug screen may be favorable for opiates and PCP.


Diltiazem (Cardizem) is used to treat hypertension (high blood pressure) or slow your heart rate if you have atrial fibrillation. If you’re taking diltiazem, your urine drug screen may test as a false positive for LSD.


Diphenhydramine is an antihistamine found in allergy medications like Benadryl and sleep aids like Tylenol PM and Advil PM. If you’ve taken diphenhydramine, your drug screen may show a positive result for opiates, methadone, or PCP.


Used for sinus and nasal congestion like Sudafed, pseudoephedrine can cause false-positive tests for amphetamine or methamphetamine.


Ibuprofen, which is Motrin or Advil, and naproxen which is Aleve, are two widespread over-the-counter nonsteroidal anti-inflammatory medications (NSAIDs). If you’ve taken either of these, your urine screen may test positive for barbiturates or THC, and Ibuprofen may also show a false positive for PCP.

Get Help at Allure Detox

If you or your loved ones suffer from an addiction, let Allure Detox get you started on the right path. Allure Detox can help, and we are a comfortable and evidence-based drug and alcohol detox in West Palm Beach, Florida. We can free you or your loved one from the physical symptoms of addiction and start you on the path to recovery.

We offer detox from drugs and alcohol on a medical basis so that you can safely resume the life you once lived, the life you thought was lost forever. Addicts emerge from Allure Detox healthy, sane, and prepared for a lifetime of recovery. Please contact us today if you or someone you love is suffering the pain of addiction.

Published on: 2020-12-27
Updated on: 2024-06-19