False positive for tricyclic antidepressants in urine test?
I recently was tested by my parents because I have been caught using marijuana several times. They bought a 10 panel drug test from CVS pharmacy. I ended up failing for tricyclic antidepressants and obviously marijuana. The problem is that I dont even know what TCAs are but I do know that I have never taken anything of the kind. Before the test I had smoked marijuana the night before (no the weed was not laced with anything and dont respond saying it was cause it wasnt I went with my buddy to a dispensary and he bought it from there, I live in Cali where people can get marijuana cards to legally buy pot from stores that know what they’re talking about not of the street) and had taken 100mg Diphenhydramine Hydrochloride also which is simply a sleep aid. What could have caused the false positive if anything? I know these tests are faulty. DO NOT REPLY IF YOUR GOING TO TELL ME WEED IS BAD, I DONT CARE YOUR NOT MY MOM.
Thank you for that I usually can find that stuff on the web but couldnt this time. I knew that diphenhydramine could cause false positives for other substances but I was just clueless as to tricyclic antidepressants are. Saved me from a lot of explaining. Can’t thank you enough.
I will bet it is the diphenhydramine. You are sort of right that it is a sleep aid but really it is an antihistamine (Benadryl) that causes some sedation. You also took a very large dose, twice the recommended.
Diphenhydramine is well established to cause a false-positive, especially at high doses for tricyclic antidepressants (TCA’s). Even though diphenhydramine is not a TCA is can still be positive.
False-positive results for TCA’s may occur from the following drugs: Benadryl (diphenhydramine), Flexeril (cyclobenzaprine) Seroquel (quetiapine), Tegretol (carbamazepine), Trileptal (oxcarbazepine), Mellaril (thioridazine), and Thorazine (chlorpromazine), and Zyrtec (cetirizine).
Depending on your situation your parents can have a test confirmed by sending a urine sample for GC-MS testing which is conclusive where as what they used (enzyme immunoassay) is not conclusive.
Also note that TCA’s are NOT substances of abuse, they are not addictive, they have no recreational value (ie no euphoria or other pleasant effects), they are not federally controlled substances under The Controlled Substances Act nor are they controlled under California State law.
For information on TCA’s drug testing:
Additional information about TCA’s
Here are links to the official prescribing information for two TCA’s for more information:
Nortriptyline prescribing information:
Anafranil (clomipramine) prescribing information:
Diphenhydramine can trigger a false positive for TCA’s.