What Drugs Are Likely To Interfere With Urine Drug Screens?

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Drug testing/screening is a common procedure enforced by most companies during the hiring process as well as post-employment. It is a mandate in certain safety-sensitive sectors as well, in order to ensure workplace safety. It is mainly conducted for determining if an individual is abusing any substances, with the most common mode of testing being urine tests. False positive results after undergoing workplace drug testing might sound alarming and are more common than you think, but are nothing to worry about if you have valid reasons to back them up.  They can be either the result of a testing error in the lab or due to medications that you are taking. Here is a list of 10 prescription and over-the-counter medications that can result in a positive drug urine test.

Prescription meds that can result in false positives

1. Dextromethorphan (Delsym, Robitussin)

Dextromethorphan is the key element in most OTC cough suppressants like Delsym, and Robitussin and may render your result positive for PCP.

2. Decongestants

Pseudoephedrine is used in most decongestants like Sudafed to cure nasal and sinus congestion and may cause false positive results for Methamphetamine and Amphetamine. 

3. Diphenhydramine (Benadryl)

Diphenhydramine medicines like Benadryl are used for treating allergies, colds and itching and may result in false positive results for certain opiates and opioids and sometimes, although rare, for PCP. 


NSAIDs are a group of nonsteroidal anti-inflammatory medicines like Naproxen (Aleve, Naprosyn) and Ibuprofen (Motrin, Advil). They are used for treating fever, pain and inflammation. Although rare, taking OTC NSAIDs can render your urine test result positive for THC or Barbiturates. Oxaprozin (Daypro), is another NSAID used to treat Arthritis and can result in a false positive test result for Benzodiazepines.

5. Phentermine

As an FDA-approved drug Phentermine (Adipex-P) is used as a weight loss medication that works by decreasing one’s appetite. Taking Phentermine can return false positive test results for Amphetamines.

6. Antidepressants

There are many antidepressants that can result in false positive results after taking a drug urine test. Some of them are listed below:-

  • Desvenlafaxine (Pristiq) and Venlafaxine (Effexor XR) are SNRI antidepressants (Serotonin-Norepinephrine Reuptake Inhibitors) that render a test result positive for PCP.
  • Taking Sertraline (Zoloft) as an SSRI (Selective Serotonin Reuptake Inhibitor) can result in a drug test returning positive for LSD  and Benzodiazepines.
  • Trazodone an antidepressant that may result in a false positive drug test result for Methamphetamine and Amphetamine.
  • Taking Bupropion (Wellbutrin XL, Wellbutrin SR) may show a result positive for Methamphetamine or Amphetamine.

7. Quetiapine

Quetiapine (Seroquel) is an atypical antipsychotic that is used to treat mental health ailments like Schizophrenia and Bipolar Disorder and can cause a false positive test result for Opioids like methadone. 

8. Quinolone Antibiotics 

Quinolone like Levofloxacin (Levaquin) and Ofloxacin is used for curing bacterial infections and can cause a positive test for Opiates, Methamphetamine or Amphetamine.

9. Promethazine

Promethazine medicines help treat vomiting and nausea and can render your result positive for  Methamphetamine or Amphetamine. 

10. Proton Pump Inhibitors

Proton pump inhibitors also called PPIs are used for treating heartburn and GERD (Gastroesophageal Reflux Disease). PPIs like Pantoprazole (Protonix) can show positive results for THC.

Choose Affordable Rapid Testing, AZ for 99% accurate drug test results

A false positive test result, as alarming as it sounds, is nothing to be afraid of if you have a valid reason to back it with. The best thing to do in order to steer clear of false accusations or consequences after workplace drug testing is to come clean about every medication, food or supplement you have taken that may result in a positive result. However, companies should make the effort to avail the most reliable testing services to ensure a seamless testing procedure. Affordable Rapid Testing is one of the top testing services in Arizona with dedicated centers situated in Phoenix and Scottsdale. With optimized testing methods, they ensure maximum accuracy for every test they conduct. To know more about them, check out their official website. 

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