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False positive for drug use because of ARV

An HIV-positive Filipino – who is about to renew his driver’s license but was told that his ARV may falsely indicate he takes illegal drugs – asks about “cross-reactivity”, and Dr. Jose Narciso Melchor Sescon provides needed information on this.

Dr. Jose Narciso Melchor Sescon – president of the AIDS Society of the Philippines and current Chief of Clinics of Sta. Ana Hospital – answers all your HIV-related inquiries. For all your questions, email or

Dear Doc,

I am HIV-positive. I am about to renew my driver’s license, and I was told that my ARVs may show false positive results indicating I take illegal drugs. Do I have to disclose my HIV status to the Land Transportation Office (LTO) just so I clarify to them that I do not use illegal drugs, and that the false positive results are because of my treatment?

Confused Driver-to-be

An evidence-based study by Antje Blank, MD, from the University Hospital Heidelberg in Germany, with his colleagues involved 100 HIV-positive patients, with half of them on an Efavirenz regimen and half who were not. All of the patients were screened using several of the most widely used urine drug tests. Blank’s team found Efavirenz resulted in a false positive for benzodiazepines at 98% of the time. All 50 of the people on an Efavirenz regimen tested positive for benzodiazepines. Forty-six (46) of the people taking Efavirenz also tested positive for benzodiazepines. However, subsequent screenings with a more sensitive test revealed that only one of the 50 was actually taking benzodiazepines.  The team found no false positives for marijuana.

The authors concluded: 

“Because Efavirenz is an antiretroviral drug that is often given to HIV-infected patients, it is therefore of utmost importance that clinicians and patients know about this cross-reactivity to avoid incorrect assumptions about the client being a potential illicit drug user. It is then recommended further that the urine sample further be analyzed using mass spectrometry, so that cross-reaction could be mitigated.”

Note to all PLHIV taking ARVs, such as Non nucleoside reverse transcriptase inhibitor (NNRTI) Efavirenz (sustiva) and the combination ARV product Atripla (Efavirenz, Emtircitabine, Tenovofir combination), the Efavirenz component are known to cause false positive result for cannabinoid or THC (marijuana by-product) with certain drug screening assays.

We know for a fact that LTO uses urine samples as screening tool for drug users; patients taking Efavirenz typically have the metabolite hydroxy-efavirenz and/or 8-ether glucuronide present in their urine. Of the two metabolites, it is glucuronide that cross-reacts with many of the drug test assays. The exact reason or mechanism for this cross-reactivity is not known.

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It is, nonetheless, a good thing that urine drug testing is under temporary restraining order (TRO); meaning, in the Philippines, drug test is no longer a requirement to get a driver’s license.

But it is good to know by all PLHIV that such cross-reaction occurs. If, in the event this is needed, a PLHIV may need to have doctor’s prescription that the client is on ARV medicines and this will be presented prior to urine drug test. Should this result turn positive, specific drug test such as spectrometry is recommended to dispel cross-reaction. Whether to disclose your HIV status or not, or whether this will help you or not in your application depends on you. But remember that ones HIV-positive status should be held confidential at all times.


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