More About Drug Screens

Working at an opioid treatment center, I get questions frequently from patients who are concerned about their positive urine drug tests. Overall, the tests are pretty good, but false positives can, and do, occur. Every different lab tests the urine samples with different reagents, or chemicals, so the doctor at your opioid treatment center should know what can cause a false positive at your particular lab.

First, a little about cocaine. The test for cocaine is very specific. The only thing that causes a positive for cocaine is cocaine. Despite similarities in the name, Novocain and lidocaine don’t cause a drug test to be positive for cocaine. No, it can’t be absorbed through the skin enough to give a positive, and if you are so close to cocaine that you’re handling it, I would say that counts as a positive anyway. Yes, it can be absorbed through mucosal lining – oral, vaginal, rectal – and again, that’s a true positive.

Benzodiazepines are a different story. I’ve worked at clinics where diphenhydramine (Benadryl) causes false positive results. That is, the patient didn’t take benzos, but the diphenhydramine made their test positive, so it looked like they are using benzos.

I tell patients to avoid diphenhydramine, which can be difficult, since it’s in most of the over the counter sleep aids. But diphenhydramine does interact with the metabolism of methadone, and needs to be avoided.

I had a patient test positive repeatedly for benzos, and she swore she wasn’t taking them. I believed her, and had her gather all the medications she had at home, prescription and over the counter. When we looked at them, she had a bottle of some kind of herbal stress-relief medication. On a hunch I asked her to stop this pill. Within two weeks her urine drug screen was negative.

I’m convinced this herbal remedy either contained a benzo, or a substance that caused a positive for benzos. There’s no FDA oversight with these herbal remedies, so the contents may or may not actually be what’s listed on the label.

So if you are testing positive for benzos, and know you haven’t taken any, consider stopping any herbal medicines that you are taking.

21 responses to this post.

  1. Herbal remedies take a long time to effect but at least they are way safer than conventional drugs“,


    • Actually, no, they aren’t. We have no safety data on herbal remedies, since they aren’t controlled by the FDA. Many herbs are fatal when injested, in fact.


  2. herbal remedies are the best! i have some sprains and some indigestion and herbal remedies cured it-;.


  3. i used to do herbal remedies when having some muscle pains and they are really quite effective ;.:


  4. Was this Valerian Root? It is an herbal remedy that has similarities to benzodiazepines in that it acts on the GABA alpha receptors…I am not a big believer in herbal “remedies”, but I ended up taking Valerian Root quite a bit these past few months (I am on MMT). I had no idea that it could cause a false positive until it happened to me – it was my first positive for anything ever in 6 months of treatment and they immediately cut my dose from 110mg down to 60mg in about 10 days. It was horrible. I did retest and it came back negative, and the nurse/counselor/doctor have all acknowledged that it was a false positive; however, I am still only at 80mg and they are not allowing me to go back up. I have been in treatment over 6 months and have done everything right including never being late on payments, never missing an appointment with my counselor, never missing a day, and no positive UAs, etc. I was amazed that after one FALSE positive, they would do this to me. I am committed to recovery and I do absolutely understand that the staff deals with addicts every day and therefore have reasons to not trust me, but why drop me so fast? And not let me go back up? And they also haven’t allowed me to have take-homes back. Is this normal? I have been dealing with a lot of BS at the clinic – they lost my blood tests, they did a tuberculosis test 3 times because they lost those results, the nurse told the doctor I was pregnant before an appointment one time and the doctor freaked out until I corrected her (don’t know why that happened), they have forgotten to record my payments (good thing I save receipts!)…I mean, am I incorrect in thinking that this is absolutely unacceptable for a medical facility?
    I was stable on 110mgs – I would get sick in the mornings but it wasn’t something that I couldn’t deal with, and I don’t expect everything to be perfect…I know I have to work hard at this. However, I’m now at a dose that I am not comfortable at in the least – I feel sick from early afternoon on, and by nighttime it gets bad. And the cravings are back full force. I am taking extreme amounts of loperamide (I’m sure you know, this is an opioid that does not cross the BBB) to cope with the physical symptoms. I have PTSD and the mental problems are also extremely hard to overcome…I’ve been having panic attacks very frequently. I have told the clinic this and they don’t seem to care, they just brush me off.
    Wow, sorry to unload here…I know this is an old post so I don’t even know if you’ll read this. I really do love your blog; I just discovered it and have been going through the archives. Just had to comment on this one and share my experience with the false positive – Valerian Root CAN cause this to happen, everyone, so be careful! If you have time to give me some feedback on my story that would be great and so much appreciated, as I am still in a bad position. I was thinking of contacting NAMA or the State Methadone Authority but I am so scared to be on bad terms with the clinic.
    Thanks for being an advocate for MAT, it really does save lives…addicts are people too.


    • Actually, Valerian root was on the label. But when we did a more specific test (GC/MS), it turns out that her urine sample contained diazepam. I suspect this herbal compound had diazepam added to it during manufacture. There’s essentially no analysis or oversight on these type of compounds.

      Either that, or she wasn’t being honest, and actually had taken Valium.

      As for your troubles with your clinic…most clinics do have grievance procedures. When a good clinic receives a patient grievance, the clinic takes time to re-evaluate treatment decisions, to make sure the patient has had fair treatment. After all, no one is infallible, and sometimes other treatment team members can see mistakes made in a patient’s care. There’s no guarantee that you’ll get the decision you want, but it is a way to ask staff to re-consider decisions that have been made.


  5. Posted by Googeram on July 21, 2013 at 3:13 am

    Wasn’t diazepam once extracted from the Valerian plant? It would seem that if one took a very large quantity of Valerian root, metabolites of diazepam or it’s anologues would be present.


    • Nope, diazepam is man-made; a scientist at Hoffman-LaRoche made it in the early 1960’s. However, compounds in Valerian root called valerenic acids may act on the same brain receptors (GABA) as sedatives. But chemically they are different.


  6. Posted by Shanta on March 16, 2016 at 7:17 pm

    Please advise: I recently tested positive for benzodiazepines, and have not taken any benzos in over a year. I take herbal supplements, which triggered my interest in this article. I am currently waiting for the specific lab results, but I am convinced it is herbal supplements that are responsible for the false test results. What herbal supplements was this woman who was mentioned taking? Is there any possibility of the test results being positive for benzos when herbal supplements are taken in conjunction with prescription pills? Could taking a SSNRI and some form of herbal supplement cause this? (Eg. Kava Kava, Kanna, Valerian Root etc). It is extremely imperative that I discover what could have caused this false positive, as many factors are on the line, and no one believes me when I state that I haven’t taken any type of benzo. When the lab results come back, do they determine what caused the result? Will it clearly state that it was not a pharmaceutical substance? How long do lab results typically take to get the results? I am filled with anxiety and angst trying to figure out what caused this result in my urinary analysis results. I have stopped taking any herbal supplements, but it’s critical to determine what caused these results, and what prompted them. If anybody has any information at all, it would be greatly appreciated. There is no clear information online regarding this very specific subject. Thank you.


    • It could be something in the herbal stuff – no agency checks those to see what they really contain. If the herbal medication contains benzos, it will test positive just like you consumed a benzo pill. I know of no way to know the difference.
      About the only way you could be sure is to find some lab willing to test your herbal medication to see what it really contains.
      this can cause real problems for patients, which is why I don’t recommend herbal medications.


      • Posted by Brenda on July 26, 2017 at 6:52 am

        It is so unfair to us as patients to be taken through mental, emotional & physical anguish. My Dr. has been prescribing hydrocodone. He said that he don’t want me to take Valium. I have taken it periodically where it was prescribed by another physician for anxiety. I have never had a problem with abuse of 5 to 10 mg. of Valium, or anything else. However, he had me to sign a drug agreement. I have chronic back pain, along with many other issues of pain. He said benzos showed up in my urine, and wants me to register with a drug abuse clinic. I told his nurse that I will go to pain management, but not drug abuse. His nurse wants to give me the number to the jail. This is just wrong. I try to explain that it could be the essential oils that I am using, or the GABA, and Valerian root that I am taking. Even if I take a valium every now and then, none of this is drug abuse. The Dr. refuses to talk to me. His nurse says that he told her to tell me that she handles everything. See, my blood pressure and other ailments were getting better with the herbs and essential oils. I take the Valerian because he doesn’t want me to take the diazepam(Valium). I have never smoked nor drank alcohol. I believe he doesn’t want me to get better. His nurse told me that he said to find another physician. I’m really going through a lot of pain right now. Emotional as well. I pray that God sends me a good physician that cares & love people. I will be 60 next month. It’s hard times. I should not be going through this.

  7. Posted by Brandi on April 13, 2016 at 11:10 am

    Good stuff, thank you for your insight. I must say your willingness to check into false drug test is refreshing. I was on Methadone for 12 years, I’ve been clean from Methadone 5 years but no drug addiction for 17 years. I’m lucky the Methadone clinic has great testing. I did get a false cocaine test, I told my counselor “I have never been positive in the 3 years prior this test and I won’t be positive ever after this test. I don’t use cocaine, it has no effect on me!” she took it off my record but I didn’t find out for years. I have a question, and i feel that with your honesty and kinda occupation you could give me the best answer. My husband had a set back and wound up in jail, he got on Subutex and about 30 days later came home. He had a broken wrist, and also has hep c. Were not sure if the hep has damaged his liver but he’s had it over 10 years. So he continued faithfully going to the suboxen clinic and faithfully was coming up positive for drugs he doesn’t do. One week it oxycotten, the next it’s ecstasy (MDMA), speed, than ecstacy again, herion, actually herion a few times and they finally kicked him. What’s odd to me is, week one it’s speed, week two it’s herion without speed, week 3 ecstacy only, never did more than one substance show, so he never had two drugs in his system at once according to the UA tests. If he was still doing herion and somehow I was blind to it (doubtful) he wouldn’t not have stopped herion to do ecstacy, but more over ecstacy isn’t a daily drug. He definitely wouldn’t have stopped using herion while using speed. If he was using, he wouldn’t stop one to do the other. He’s an addict, “does using 2 different drugs at once make the drugs twice as good?” That’s how his addict thinks, separating drugs is a waste. If he was using more than one drug, he wouldnt have only one substance in his sytem , he would overlapped them and it would show in tests! Now I do know he found a herion stash, and it wasnt wrapped properly, when he gave it to me (I flushed it, was livid it had been in the house) I did have to wash my hand cuz some stuck. Could he have gotten a positive from touching it? Or maybe usinging the drawer he kept his works in, but instead of using the drawer for drug paraphernalia using the drawer for something else he does daily; like sock drawer? What concerns me is a friend started that clinic (with no reason in the world to lie to us, but dope feens do it) has been getting false positive for strange classes of drugs. What’s strange and what worries me is this friend never used herion and never has. He’s in his late 40’s early 50’s. Okay strange, he’s on seboxen but didn’t do opiates?!? Not really. He is an addict just not herion addict, and has demonds he doesn’t want to face. When he went to jail he foolishly lied to the nurse about herion detox and they put him on suboxen. Witch is perfect for a non opioid dependent. Suboxen gets people without opioid dependency high in a similar way as opioids. (so I’m told) but also in jail it’s used as currency. But him coming up positive (herion) for a drug he wouldnt use is a little perplexing. But he came up positive for ecstasy, something that he says hasn’t seen in 15 years. But the speed he use’s daily is negitive.
    I’m willing to accept maybe my friend has a long nose, but I was with my husband and he wasn’t on any of those drugs! Do you think his opioid addiction could have stayed in his system due to his liver and hep c? causing a positive 30 days after use? How about his wrist that needed reset? He took Vicodin the day they reset and put cast on his wrist that was broken in 5 places.because of his wrist he was taking 3 Percocet a day until about 2 weeks b4 discharge. So roughly 3 weeks before his first UA at the suboxen clinic. With the pharmacy meds, and handling the herion we have some answer if his liver is a causing a delay in his system being flushed. But it worries me, seeing him so dedicated, and going to that clinic daily, to been kicked off for something he didn’t do. He was so crushed and angrey! He said “had I been using I could give a sh!#, but I haven’t been using!!” He did struggle after the clinic cut him, and used. He was mad he had to resort to herion use because suboxen cut him, i gave him space and didnt nagg about program. I figured id give him 5 days. But after 2 days he announced “im going to to get on methadone, i dont want to use so i have little other choice.” This is not the behavor of an actively using addict, he made the decision before i even got to ask him what he was planning. Usually nagging on my part is what pushed him into recovery. This confirmed what i already knew… He was tired, jail was a familar bottom he didnt want to see again. So it was the 3 days after suboxin clinic kicked him out he got on methadone, he only used herion once in that 3 days and hes been on methadone since. I thank the gods the false accusations didnt push him to his addiction. Its so devistating when your telling the truth, to be called a lyer. He wants to use suboxen to get him off Methadone and than slowly get off suboxin to be clean (in the no substances kinda way) again, but he’s at a complete loss. That’s the only suboxen clinic we can utilize. Do you have any advise? Besides my three questions?!? Is there anyway, that if he does go to that suboxen clinic that we can be sure tests are done correctly not creating false positives? Thank you so much for your blog and your comment section. Like I said it refreshing to hear a doctor admit that false positives happen, who works at a clinic. It’s also great to know that some clinics don’t always assume all clients are lying.


    • First, if your husband is sure he’s getting drug tests positive for drugs he didn’t use, he needs to ask for a confirmatory test. And no, handling heroin won’t cause a positive drug test. Heroin actually has a relatively short window of detection, so it’s a little unusual to get false positives for the 6-MAM metabolite for heroin.
      The only way you can know what kind of test his doctor is using is to ask…like I said, when there’s an unexpected screening test result, a second, more specific, test needs to be done, to eliminate the possibility of a false positive test result.


  8. Posted by Shanta on April 19, 2016 at 4:08 pm

    UPDATE: After the lab results came back from the urine analysis testing positive for Benzodiazepines, the results were an obvious NEGATIVE. All of the stress, hassle, and turmoil I received from probation and family services was unnecessary. Of course I got no apologies, but I was happy that I had proved myself to be clean and trustworthy. There is no explanation why there was a false positive, however, false positives are clearly more common than people (especially authoritative figures) think they are. This is the second time I have tested (false) positive. The first time I had a false positive, they said I tested positive for Ecstasy, mainly MDMA (I have never done Ecstasy in my Life). After the lab results came back, it was determined that my use of Trazodone caused the false positive result. It is unjust and unfair for legal authorities to judge others based on the results of a drug panel test, without waiting for the specific lab results to determine the outcome. I am also starting to question the apparent (positive) results of any drug panel test I have taken. I was told these tests are “99% accurate,” which is clearly a misrepresentation of these “elaborate” tests. I have been accused, belittled and humiliated by some of those in the “system.” I was scolded and told to “Fess Up” after the initial drug panel test came back positive for Benzodiazepines. It is obvious trickery and deception tactics used to see how I react to the results, and to get me admit so something (I didn’t do). I am a victim of false accusation, and will only allow this to make me stronger, and more determined to prove them (those who doubt me) wrong. If anyone reading this ever finds themselves in this situation, do not let anyone’s doubt (in you) lead you to doubt yourself. Stay true to yourself, and let their negativity fuel your strength to prevail and prove them wrong. I have researched this topic endlessly, and did not find any valuable truth or research online as to why false positives happen, or what can cause them. There are clearly MANY different substances that can cause a false positive result, and they happen more often than they are reported to. Don’t be discouraged, you know the truth in your heart, and the truth will set you free.


    • I’m glad things ended well for you. It is a shame that people assume the worst, and I think whoever quoted you a “99%” accuracy rate was 100% inaccurate. The first screening test in drug testing is fast, cheap, and relatively good, but to meet the legal standard of “beyond a reasonable doubt,” a positive drug screen has to be done chain of custody with any initial positives re-tested with chromatography of some sort.
      Screening tests are just that – screening.
      It does feel like someone should say sorry. Also sounds like any positive screen shouldn’t even be released until it is checked with second test, to avoid the distress you had to go through.


      • Posted by Shanta on April 20, 2016 at 2:22 am

        Thank you for the comment. Support and strength comes from the sources that you would least expect it at times. I truly admire your insight and your blog has really given me a restored faith in humanity. Thank you for continuing to post valuable information and educational content. Knowledge is power, and when we take the time to engage in self reflection from our experiences, it strengthens our core, so that we can live a wholehearted existence within the Universe. I am grateful that I came across your blog, and continue to read and enjoy it on a regular basis.. This is sent to you with much appreciation, respect, and admiration. Thanks again!

  9. Posted by Kathy Haven Gilbert on February 3, 2017 at 5:48 pm

    I know this post is over a year old but it peaked my interest. Im in pain management and get tested every month. I was honest with them about 3 months ago and told them I had taken 2 msg of Valium the night before the test. It was from an old script, which they easily verified at the pharmacy. They directed me to stop taking it, which I did but I’m still showing positive as of last month. I have very bad insomnia and had started taking Valerian Root, SkullCap, Melatonin and Benadryl to try to help me sleep. Is it possible that these meds are causing a positive for a benzo. I also use the Benadryl for motion car sickness. I’m terrified that I’m going to lose my pain management.
    Thanks for any info,
    Kathy from Syracuse


    • I’ve had several patients in the same situation and I think the over-the-counter products sometimes do have benzos in them. Those patients have also continued to test positive for benzos AND confirm positive for benzos while they deny taking benzos. Keep in mind too that nordiazepam and other metabolites from Valium stay in your system longer than alprazolam. Still, I wouldn’t expect a one-time dose of Valium 2mg to stay detectable in the UDS for more than a few weeks at the outside.


  10. Posted by Shanta on October 11, 2017 at 8:03 pm

    I have posted regarding false positives in the past. Unfortunately I have another experience being falsely accused of using drugs. The drug that I was prescribed was Gabapentin, and this sent out a false positive for fentanyl on a Biotech Urine Drug screening test. I stopped taking it and my screenings were fine. Please also note that I was on a high dose of Venlafaxine, and this caused a false positive for tramadol. I also tested positive for alcohol, and did not have any. Please note that these results were disputed, and the tests I believe were all negative, as they had faint lines in the negative column. The lady who administered the test had only used this type of test once before (UTOX Test) and no experience with it. In fact, Biotech Labs had not even published all of the literature on it yet. Also, upon discussing the situation with a Biotech Lab technician, they confirmed that ANY and ALL questionable drug screening results should be sent away for further testing. After fighting in court for not being allowed to get (multiple) “false positive” test results sent to a lab for further testing, two months later I finally proved my innocence. They said I tested positive for fentanyl and when it was sent away for further testing, it was completely negative for all substances. So if you are on gabapentin, and getting regularly drug tested, please be aware that you may test positive for fentanyl on a drug screening panel. Hopefully you won’t have to endure all the hardships that I did.


  11. Posted by Sherry Colby on February 1, 2020 at 2:26 am

    I am on probation and supposedly tested positive for fentynal. I am on suboxon among other medications and take benadryl. My probation officer was going to put me in jail but my Lawyer told the court I am willing to do a hair test which can’t be done for 3 weeks. As a result I am now on house arrest until I can get the hair test that I have to pay for. I know that it will be negative as I haven’t used ANYTHING at all accept my prescribed medications. Is there anything that can be done about this situation? I am very distressed and suffering from anxiety panic attacks due to their erroneous testing. Also they expect the same company to do my hair test is this legal? As it is I’m afraid to do anymore drug tests at this place for fear of another false positive.


    • It still surprises me how probation officials put people in jail with only a point-of-care test. They should be doing confirmation testing too, to avoid false positive screens. That’s especially true when someone’s freedom depends on an accurate result.
      They can do hair testing, but it’s less efficient at detecting one-time use of drugs, and dark-haired people tend to concentrate drugs into hair more than blondes. That means it’s a biased test too, and I have a problem with that.
      If you haven’t used any drugs, the hair test will likely show that, and I know they are more expensive. Around here they are $100 per test or more, depending on how many drugs are tested for.


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