Will An OTC Sleep Aid Containing Diphenhydromine HCI Can Cause A False Positive Drug Screen?

Posted on Tue, 29 Oct 2013

Question: What is the likelihood that taking an OTC sleep aid (once to twice weekly) containing Diphenhydromine HCI can cause a false positive drug screen?

Answered by Dr. Roopa Hiremath (2 hours later)

Brief Answer:
False positive drug screen possible

Detailed Answer:
Hi Ms. XXXXXXX

I understand your concern regarding a positive drug screen.

Drug screens are usually done to detect common drugs of abuse.

Coming to Diphenhydramine Hydrochloride, this drug commonly known as Benadryl is an antihistamine used for treatment of common allergies and is available over the counter.

There are reports that Diphenhydramine causes false positive drug screen tests especially for drugs like Phencyclidine.

But doses as small as 25 -50 mg once a week most probably will not interfere with the drug screening test.

However, screening test results are confirmed by doing confirmatory tests like gas chromatography mass spectrometry (GC-MS) to reduce the rate of false positives.

Detailed medical history is also taken before doing any kind of drug screening test to rule out drug interactions.

I hope I have answered your query satisfactorily.

Thanks.

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Above answer was peer-reviewed by : Dr. Shanthi.E