Skip to content


    Attention All WebMD Community Members:

    These message boards are closed to posting. Please head on over to our new WebMD Message Boards to check out and participate in the great conversations taking place:

    Your new WebMD Message Boards are now open!

    Making the move is as easy as 1-2-3.

    1. Head over to this page for your Smoking Cessation board: this page for your Substance Abuse board:

    2. Choose the tag from the drop-down menu that clicks most with you (and add it to any posts you create so others can easily find and sort through posts)

    3. Start posting

    Have questions? Email us anytime at [email protected]

    Includes Expert Content
    Can Ibuprophen and Naproxen Sodium cause a false positve for THC?
    brad2011 posted:
    I tested positive for THC this week even though I haven't smoked marijuana in over two years. I did take 1 Aleve and 2 Ibuprofens the night before the test and then 3 ibuprofens that morning because of a sore knee. After testing positive around 11am, I knew it had to be wrong so I bought a home drug test kit and tested clean at around 7pm the same day. I even went to a "doc in a box" type walk-in urgent care facility the next day to have a more accurate urine screen performed and I got the results back today and they were negative, too. So again, my question is, could either the Ibuprofen or the Aleve, or even a combination of both have produced a false positive for THC? Please help me so that I can avoid this in the future...

    Take the Poll

    Has anyone else ever tested positive for THC after taking ibuprofen and/or naproxen?
    • Yes
    • No
    View Poll Results
    Betty Ford Center
    James Golden, MD responded:
    Both Aleve and Ibuprofen can result in a false positive test for THC. With newer testing methods, we can run confirmatory cross-checks to check for interfering substances, such as metabolites in these medications.
    stick312 replied to James Golden, MD's response:
    I recently took five urine tests on successive days. I began taking Aleve for tendonitis in my elbow during that time not knowing it might impact the test results. Turns out the last three all tested positive for THC. I contacted Bayer directly and they had no information on file that Aleve would cause a false positive for THC. Where can I get reliable substantiation this could happen?
    Betty Ford Center
    James Golden, MD replied to stick312's response:
    This guide from the Mayo Foundation for medical Education and Research offers extensive information that may be helpful:
    Grundo replied to James Golden, MD's response:
    I recently test positive for thc. I don't smoke but I did take naproxen for my back that morning. When the doctor called me to tell me I failed I asked what my level was and he said 47ng. If its under 50 isn't that a negative? Will naproxen give you a false negative? Is there such a thing as a false negative? The doctor from the lab says no way naproxen will give you a false negative. What should I do?
    An_254060 replied to James Golden, MD's response:
    I just did & that is the only thing I take. May I ask a question? Aside from living with (part time, someone who is a smoker) I am 40 yrs old and have a zero tolerance for that crap. I never really did. Maybe before I was 20. Never, I do not care how many people want to judge or say this or feet swell 3 times larger than my shoe size and my legs die all day and are very painful from a condition i have, however, the result was a 9. Thats not even failing level. Its not even usage level. Apparently I spoke to the lab there and they told me this, specifically asked me about naproxen and yes it sits on my counter every day as I need it often to wear shoes. What does anyone have to say about this? They are recalling it based on I passed the very next and oddly I had a drug test a day before and nothing came up, so what is the deal here? I can honestly say I am not a smoker, I never liked it and I never will. This is an urgent matter and no, Im not on probation, but for other reasons it is urgent. Can someone help answer this question? My mind was blown when they called to say sorry after and are rescheduling things, however, I need to know WHY? Is it really true this would have an effect and if so how? Such a low one at that. Not even failing level. If I had made failing level they would have went about things differently but I did not even make that so my lawyer postponed (custody arrangement Issue) ...... however my son is begging to come home, begging, He is 12. Please. Tell me what I did or can do or why even? It is not going to rely on this however I cant understand it. Just looks silly to the judge, but it was not failing either so he was understanding and just needs to know. I have a few thoughts but to be honest, Idk if they would even be an answer. First of all I had a huge party at a friends the night of my 40th birthday. I do not drink, so its not like anything went into my body that night. My lawyer said poss 2nd hand but I say no to that. It bothered me he even said that!!! Do not make excuses for me...! I know myself and If I say, I did NOT do it, Im saying I did not do it.Some people will give you a load of bc for an answer, however, my son is my only son and I could care less about a glass of wine, any drugs, or even lobster or new clothes. HE, comes first, period. I would never and have never jeopardized that. Now, my ex is laughing and screaming profanity as I left the court house. If I left my car open ever, and left my coffee in there daily as I do, could anything at all, anything had ever be put in it? I would not be surprised as he disassembled my last car just months ago. One thing, if you are on someone's car everyday (bc temp yours is not running at all), and they drive with someone who DOES smoke and does so in the car, could that in ANY way at all do this? I need to now because if so, I can never and will never get in that car again. I'm renting a car tomorrow by the way just in case b/c that is my only thought aside from the as needed Naproxen Sod..anti inflammatory... ....Please, may an expert Please, help answer this question. GBY for answering or helping in Any way.
    ljude38 replied to James Golden, MD's response:
    I had no idea about this. Thank you for the info.
    tucker22 responded:
    Yes, I just tested positive for THC. I could not understand why. I have passed drug test before without problems urine and swab tests. But I am just now finding out about these false positives with Aleve. I did take Aleve and was taking prescription for Alprazolam. I told them about the prescription but forgot I also took Aleve. I am going to let them know and hope they will re-test me. Because I stopped taking both.
    ryandaniels69 responded:
    Last week I had a urine test done. I take them every 2 weeks. I haven't had any prescription medication for 3 weeks and tested positive for THC. I haven't even smelled a roach in 5 years. It was for traffic probation and the counselor had me pour the urine in a second test cup. It tested positive as well . The ONLY medication I had in the last 4 days was Aleeve. I blew out my knee and was taking about 10 a day. I know ,,, more than I should have ,,, but the pain was UNBEARABLE . I had to go to a private test lab and take a test out of my own pocket or violate and go to jail. I paid the $ 50.00 and took the test ... NEGATIVE for a 10 test panel . I know pot stays in your system the longest and wouldn't mind taking a poke every now and then. But with 7 weeks to go on probation,,,,, I'm NOT stupid !!!! The counties test kits are the cheap older ones and the CDC has stated that high doses can cause a false positive.
    shrbear3 replied to ryandaniels69's response:
    I have ran into similar situation on 3rd of June I took a random for my pain management Dr. (keep in mind I been in pain management for about 10 years) today I went in for procedure on my neck(RFA treatment) he says that I tested positive for THC! Knowing my Dr I started laughing saying that's funny. He then was asking if I have smoked any, I have in past years ago he was made aware cause I don't hide anything from my Dr they can't help me if I'm not open with them. Anyway I asked if he was joking cause truly believed he was cause haven't smoked any weed in bout 5years. Only thing different from last random is I have been taking a butt load of Aleve Midol Motrin and BC powders cause I am been hurting so much. They now discharged me and have to find another Dr. Is there a way to challenge this? What can I do? Now I'm scared to get randomly tested at work!! That's my job!;!;
    An_264634 responded:
    I tested positive for cannabinoids and I do not smoke pot. At my Doctor's suggestion, I take Ibuprofen with my Tramadol, when needed. I then had to have lab do a more extensive test, which came up 10% ng/ml. Now I must go to a court hearing to see if my diversion should be revoked. I am 62 years old, and never been in any trouble in my life. until I made the mistake of trying to move my vehicle in a parking lot. I have done everything my diversion called for in the last 8 months. Is there any hope for me?
    zelda88 responded:
    I took ibuprofen just before my drug test today and tested positive for trace amounts of THC? I don't smoke pot or do drugs nor have I ever? So why the positive? I'm really upset over this. The only other thing I can conclude is a Christmas party I went to not even a month ago and when I was sitting outside by the fire the people next to me were smoking it. I agree I'm over weight by 40 lbs and I'm thinking I was subjected to second hand smoke and it stayed in my fat cells? I really don't know? I'm very upset about it and despise anyone I know now that has ever smoked around me because I'm so straight and boring when it comes to drugs and alcohol I just don't do them.

    Featuring Experts from Betty Ford Center

    Harry L. Haroutunian, MD., is an internationally known speaker on the topics of Addictive Disease and its treatment. He is Board Certified in Family M...More

    Helpful Tips

    Will smoking weed effect my everyday life and health due to my age?
    I'm 14 and I've been smoking marijuana since I was 12 due to family problems&a family loss and my grades seem to me slowly going down ... More
    Was this Helpful?
    1 of 1 found this helpful

    Related Drug Reviews

    • Drug Name User Reviews

    Report Problems With Your Medications to the FDA

    FDAYou are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.