drug test

Will Phentermine Show Up On A Drug Test?

One concern for many people taking phentermine is that phentermine is said to give a false-positive result on an employment drug test. In response to the many questions we’re asked about phentermine and drug tests, here we explain more about the drug screening process, why phentermine can give a positive result, and how to avoid this causing problems with your employer.

What Does The Drug Test Look For?

Drug testing is an action that an employer or prospective employer can take to determine if employees or job applicants are using drugs. Rather than acting as a test of impairment or whether recent behavior is as the result of drug use, employment drug tests are implemented to create a safe working environment for all employees. Workplace drug testing aims to deter employees or potential employees from taking drugs, to be able to identify and help employees with drug and/or alcohol problems, to protect the general public, and to comply with employment laws and regulations. The most common method of drug test is urinalysis, and will most typically test for five categories of illegal substances. Known as a 5 panel drug screening, this test looks for evidence of THC, Opiates, PCP, Cocaine, and Amphetamines.

In the event of a positive result in both the initial and confirmation tests, the medical review officer (MRO) then reviews the results and contacts the individual to make sure that there are no medical or other reasons for the result. It is only at this point that the MRO may report the results to the employer. Certain medications can cause a false-positive result on the drug test. If this is the case and the employee can verify that he or she has been prescribed the medication and is taking it as instructed then the test is reported as negative.

Keep reading, or check out the infographic below, to learn more about phentermine showing up on these exams.

Will Phentermine Show Up On A Drug Test?

Although phentermine is not an amphetamine, its chemical structure is similar to that of amphetamine, meaning that phentermine can give a false-positive result for amphetamine in a 5 panel drug screening urinalysis. However, following the information above, with evidence of your prescription from the doctor who prescribed you phentermine, then the result should be declared as negative. A key factor is that you have to have been taking it as directed, so this is another reason to be sure to follow the prescription and not to take more than directed by your doctor.

drug test

If you have been taking more than the recommended dosage then excess levels of phentermine might raise questions for the MRO reviewing the positive result. Although phentermine is not an illegal drug, it is controlled substance, listed on page 12 of the Drug Enforcement Agency’s January 2016 List of Controlled Substances, and can only be legally obtained by prescription. If you cannot provide a prescription to explain the presence of phentermine in your system following a drug test then this would be considered illegal usage and the MRO may insist that the positive result stands.

If you know that your employer may request a drug test during the duration of your phentermine prescription then in some circumstances it may be better to inform your direct supervisor that you are taking phentermine and to provide proof of your prescription before a drug test. This will avoid you having to retrospectively disclose that you are taking phentermine and the possibility of a false-positive reading being declared to your employer.

How Long Does Phentermine Stay In My System?

Due to confusion between phentermine and the now banned weight-loss medication Fen-Phen, as well as a general misunderstanding of what phentermine does, many phentermine users choose to keep phentermine a secret. Therefore, it is not surprising that some people may prefer not to disclose that they are taking phentermine to their employer. To avoid the possibility of a false-positive result, if you are aware that you will have a drug test soon then you may prefer to stop taking phentermine for a few days. We are often asked how many days phentermine stays in your system, and although this varies depending on the person and their urinary pH, the medication has a half-life of about 16-31 hours under normal conditions. So, phentermine should not be detectable in the urine after a period of around four or seven days. It may, however, be detectable for longer if you were taking more than prescribed or used phentermine for a long time.

If you’re concerned about a false-positive result on a drug test due to phentermine then another option is to take a phentermine alternative such as Phen Caps instead of phentermine. Phen Caps will not show up on a drug test as they do not contain ingredients similar to amphetamine, so you can benefit from the appetite-suppressing effects and energy boost without the worry of failing an employment drug test.

Have you received a false-positive result on a drug test as a result of taking phentermine? Let us know your experiences by commenting below.


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65 Responses

  1. I did receive a positive result on a drug test and showed my prescription to the nurse at work but they still sent me home and I have to wait for the lab result – I had no idea I would fail a drug test with diet pills. I don’t know what is going to happen, they said someone is going to call me, I think to ask me about my prescription, I just don\’t want to lose my job.

    • It is good to get a note from your doctor stain he or she has prescribed Phentermine for you.The reason is not required because weight loss is only one.This should be sufficient the amount prescribed is between you an your physcian.
      Other uses although not FDA recognized is for adults with ADHD.esp.if Adderall is ineffective or its side effects are pronounced hyperanxiety and excessive symptoms ,a person may be too sensitive for metabolic or endocrine reasons.
      Phentermine is also used to stop smoking .For me a note from my physcian stain I was on Phentermine and if the employer had questions or concerns to please address with the physcian. This is a reminder that employers have a responsibility to the employee and must honor hippa.,confidentiality.Verification u r on it by ur doctor should be more than enough .

  2. I’m sorry about that and I didn’t see this sooner I had the same issue but it was for pre employment. Everything went well for me and I hope it did for you as well.

  3. I tested positive for amphetamine gave all 3 prescriptions but medical review said it wasn’t this amphetamine in my urine which I didn’t understand due to that was all I was taking. Sadly to say I got termed.

    • I\’d recommend suing your previous employer if your story is true. This is a medication used to treat a real medical issue. You have as much of a case as a diabetic whose insulin caused them to come up with a false positive for amphetamines. The GC/MS test will put an end to what was really in your system and it should have been ran.

    • I just went through same situation, except, I have been with my employer, a year. I take phentermine 37.5 and for awhile now, I took the test and tested positive for amphetamines and the MRO decided that is was in no way my phentermine and I have NOT taken anything else! I am beyond pissed and have no idea what and where too go next

  4. It CAN cause a false positive on a standard “dip” test if you take it often, but then it usually goes to a lab for the final determination of what it is, and phentermine isn\t something they specifically look for. So all should be well.

    • What if i took it one time 48hrs before a 5 panel?

      • Hi Meeuh! Although it can vary depending on the person, phentermine should not be detectable in the urine after a period of around four or seven days, but will likely show-up if you take a drug test before that. Regardless, be prepared to show proof of prescription in case there are signs of amphetamines in your system.
        Rachel, phentermine.com

  5. I tested positive negative and had been taking phentermine but they called and said it showed methamphetamine molecules, I dont understand.. I’ve used in the past but its been years

    • Hi,
      Since phentermine is structurally similar to amphetamine, the tests can incorrectly identify phentermine as methamphetamine. If they’ve analyzed the results and found methamphetamine then this is strange, especially as you say it’s been years since you used. If I were you I would request that the MRO analyzes the test again if it’s possible for you to do so.
      Sally, phentermine.com

  6. Our drug testing vendor does a 3-level test on amphetamines.

    The initial test is an immunoassay, showing the presence of amphetamines generally.
    The next test is GC/MS breaking it out between amphetamines and methamphetamines.
    The third test breaks out the meth into d-form and l-form isomers, with a percentage of each.

    Is it possible for Adipex to test 96% d-meth? Please explain.

    • Hi Julie,
      We’re not sure about the exact statistics, we just know that phentermine is structurally similar to amphetamine. Perhaps it could be as similar as 96% but then that would indicate that the other 4% makes a lot more difference than might be suggested by the low number.
      Sally, phentermine.com

  7. I took about 8 Phentermine pills (30mg) over a two month period. I took it yesterday and drug tested myself with the 5 panel urine test. I was shocked to see I was positive for amphetamines. With some quick research I found out that Phentermine can lead to false positives.

    My question is, will this be detectable in my hair? I would have never taken this if I had known it was a controlled substance.

    I have a hair test January 23rd. Do you think I could test positive for this?

    • Hi Hopeful,
      We’re not completely informed about hair testing and phentermine, but we do know that hair testing is preferred in many cases of drug-testing as it shows drug use over the previous month or longer, while urine testing is limited to just a few days. However, as the article states, phentermine is not an amphetamine, it is a controlled substance in the same way that many prescription medications are. So as long as you have a prescription to show why phentermine is in your system then you have a reasonable explanation to show why you might test positive later this month.
      Sally, phentermine.com

    • hopeful
      did you pass hair test?

  8. I took 1/2 a phentermine pill today at 1:00 and didn’t think about the fact I was giving urine at 2:00 for my pain doctor. This was a 1 time thing haven’t taken it in many months. Doctor prescribed it a year ago.

    • similar. I had a prescription a year ago and took 15mg x 2 days before my drug test . I\’m worried. Did you have any issues ?

  9. I havent taken one in 5 months, just yesterday I took a half and come to find out I got the call for a job interview and a drug screen this morning is there a possibility that it will still show up on the drug screen?

    • Hi Joe,
      Yes it’s very likely the phentermine you took yesterday will still be in your system.
      Sally, phentermine.com

  10. Hello, i take qysmia and i failed a ua for amphetamines/mamp i took home test and got the same results some im just waiting on the lab has any body had this problem???? They say qysmia has phentermine in and its like amphetamines and will show up in a ua as amp/mamp…. please help..

  11. took 1/2 a phentermine pill today at 1:00 and didn’t think about the fact I was giving urine at 2:00 for my pain doctor. This was a 1 time thing haven’t taken it in many months. Doctor prescribed it a year ago.

  12. I never took phentermine. Today i took a half a pill at 1:00p.m and i took a U.A. at 830pm..i drank alot of fluids today and urinated at least 10 times easily before the test..was there enough of it to show up

  13. I have been going to pain managements for years and i have never had a bad urine screen until i was prescribed Phentermine and i was told my last test was positive for cocaine ..when i questioned my pharmacist about it he said yes it is very possible to cause a false positive for cocaine since it is a stimulant ..but im not sure what to do about this ..any suggestions

  14. I have never had a positive urine only for what i am prescribed ,,but after taking Phentermine for 2 months after being prescribed ..my pain management doctor gives me a urine screen and it comes back positive for cocaine ,,i have never did anything other then what i am prescibed ..i have diabetes and kidney trouble also …i was released from pain management ..what can i do as i have had 14 surgeries and a really messed up back and i need my meds and the procedure i was getting on my back

    • Your stuck trying find another pain management.
      But in meantime.
      Talk to your family dr about staying on your meds until you find a new pain management .
      Tell the truth to new dr.
      Make sure you tell new dr.
      Your willing to stop taking them
      That you didnt realise the severity of it.
      It happened to me.
      Same thing.
      I just found new dr.
      And told him what happened.
      That ive never had a positive urine for anything over the past 10 years.

    • I also was taking phentermine I am not drug user. I tested positive for coke now CPS has my chikdren someone please help!!!

  15. I just had to do an UA yesterday and not thinking that the medication would show up on the test. Well I didn’t pass and it has been sent to the MRO. I showed them my list of medications but I still now have to wait for the “phonecall”. I am PRAYING that I don’t lose my job over this!!! Any words of advice or wisdom would be appreciated right about now. I’ve never failed a wiz quiz… EVER! It was so embarrassing.

  16. If I took only one phentermine pill on Friday, and I have a urine screen the following Wednesday, how likely will it be out of my system? And if not, will I test positive for any substance? What about a false positive??

    • Hi Whitney,
      Although it can vary depending on the person, phentermine should not be detectable in the urine after a period of around four or seven days. In 5 days it may still be in your system and could give a false positive reading for amphetamines on the urine test.
      Sally, phentermine.com

    • Did your test come back positive? I’m in the same seat you were I took 2 pills on Saturday and 1 on Sunday, I was suppose to test today(Wednesday) but rescheduled it for tomorrow(Thursday) . Im worried it will still be in my system .

  17. I had a severe anxiety/panic attack during work and was taken to the ER. I had a 10 panel tox/UA w/micro and it came back negative. When i got home, I took my wife\’s last 2 phenties and went to bed. Boss called me 12 hours later for company UA. will it show up positive for amp/mamp? What do I do?

    • Hi!
      Unfortunately, as phentermine is chemically similar to amphetamine, it may cause a positive result in urine screening tests for amphetamine.

      • I have a question today is my first day of ever using us I took two two tablets as described and was told that I have a urine test tomorrow I\’m trying to find out since I\’ve only took two and I don\’t take it regularly and I\’ve never took it before today how long will it take my system

  18. Hi I have never took this bed or to day and I only took 2 capsules As Told I was told I would do it drug test tomorrow or the next day what is the chances that it will show up this is not something that I\’ve been taken every day I\’m new to this

  19. Hi, I only take 1/2 phentermine tablet (37.5) daily. A friend just informed me that this diet pill shows up as street drugs on a drug screen (hence what lead me to this forum). I have a drug screen in 2 days for a very strict company and I don\’t see even having a prescription being acceptable… my question is what is time frame to get this crap out of my body if i\’m only taking 1/2 daily so I don\’t look like a druggie??

    • Hi Cristina,
      Although it can vary depending on the person, phentermine should not be detectable in the urine after a period of around four or seven days
      Rachel, phentermine.com

  20. I have taken a few drug test over the period of 2 years Both pre employment and random. 2 times I was on phentermine. Both times they never raised questions. In my opinion, if you take it as directed and have a prescription for it, you should be okay. Some companies have a list of prescription drugs that they ban from any employee using while at work. So weather or not you have a prescription they can legally terminate you as long as they have a contract or employee handbook signed by you stating you read and agree with all in the book. Some people choose not to read those and when it comes to being fired they claim they didn\’t know. Hope this helps you out. If you have any concerns about what you can take while at work, simply ask for the list of drugs that banned from your company.

  21. I have taken 3 drug tests in the months I\’ve been on Phentermine and all 3 have come up positive for amphetamines. I\’ve never taken a \”real\” amphetamine in my life. There are many medications that can cause false positives for many different drugs (Tylonal, Benedryl, anti-depressiants, etc), but these false positives happen few and far between. From my experience, I\’d say you can almost expect to come up positive for amphetamines on the initial urine test if you\’ve taken Phentermine within the past few days, but I\’ve never had it tested further with GC/MS.

  22. I took a phentermine to at 8 and had to take a UA today at 4 will it show up in my unrine

    • Hi Nana, yes – it’s possible it will. Be prepared to show your prescription just in case.
      Rachel, phentermine.com

      • Thanks

  23. What are the chances of getting a false positive reading after being off of Phentermine for 45 days?

    • Hi Alex, the chances are pretty low. Although it can vary depending on the person, phentermine should not be detectable in the urine after a period of around four or seven days
      Rachel, phentermine.com

  24. I had taken phentermine a week ago then off for a week, then I took one on Saturday, today is Sunday. I will have an upcoming drug screening for new employment this week. Should I worry about it showing up? I am prescribed by a doctor but I would rather not have my new employer know reguardless.

    • Hi Sarah! That’s very understandable. Although it can vary depending on the person, phentermine should not be detectable in the urine after a period of around four or seven days, but will likely show-up if you take a drug test before that. So depending when your drug screening is this week, the likelihood varies. Regardless, be prepared to show proof of prescription in case there are signs of amphetamines in your system.
      Rachel, phentermine.com

  25. I took a phentermine Tuesday I took a random drug urine test today (Friday) I\’m so worry if be coming positive?

    • Hi Mary. Although it can vary depending on the person, phentermine should not be detectable in the body after a period of around four to seven days, but will likely show-up if you take a drug test before that. So, be prepared to show proof of prescription in case there are signs of amphetamines in your system.
      Rachel, phentermine.com

  26. I have a valid prescription for phentermine and am prepared to bring my medicine with me to the lab in the morning as proof. However, as I was reading the comments I saw alot of questions about taking 1/2 A day … I am on 2 daily – is there a level that is considered a \”pass\” or \”fail\” with a prescription? Or are they just concerned with ensuring you are taking them legally? I was thinking I wouldn\’t have any delays or issues but I didn\’t realize people took such varying amounts.

    • Hi Genny, thanks for your comment! We can’t speak to your company’s specific policies, but in general drug tests are given to determine the presence of illegal substances in your system. So, if you have a valid prescription you should be okay – regardless of your prescribed schedule/dosage. Often times people that take one pill per day are on a higher dose pill (e.g. 37.5mg), while those who take phentermine multiple times per day use lower dose pills. To learn more about different phentermine dosages/schedules, check out this page.
      Rachel, phentermine.com

  27. I take phentermine I have for a long time this is the first time I tested positive for amphetamine. I take losartan metformin Gabapentin and Zantac when their doctor called to ask me about my prescriptions I told him which ones I had and he told me that none of those could test positive for amphetamine and my job is now on the line I have been suspended

  28. I\’m perscribed phentermine 37.5 mg daily & have taken as perscribed for approximately 3 months daily. As I lost my desired weight I started to taper the phentermine approximately once to twice a week for approximately 1-2 months. I\’ve taken ABSOLUTELY NO phentermine for over a month (I actually believe 2 months. But not 100% sure). I took a pre-employment drug screen with a false positive amphetamine result! I now have to share my phentermine prescription with my potential new employer! Imagine my SURPRISE & EMBARRASSMENT! I wasn\’t prepared for my explanation because I\’d forgotten all about taking the medication (it had been so long). I really don\’t understand why it showed up in the slightest.

  29. That is surprising. I\’m wondering if it showed up because u took them for a while? I may have had 3 in my life. 2 over 90 days ago and one 28 days prior to my test. Guess I\’ll find out when I return in 3 months.

  30. Hi, I have been on phentermine for 3 months. we all get dropped regularly at work because of the work we do. On random 5 panel tests and on ones sent to the lab, neither have come back positive for amphetamines, which is great! It also makes me wonder though after reading all these posts. I have lost 34lbs, which is even more awesome, but why is it not showing up, if others do? I take my pill every morning before I leave for work at 5am. What are your thoughts on this? Could I be getting fake pills from my doctor?

  31. I\’ve taken a dope 37.5mg for 2 months,my last one was taken a week ago.I test weekly and it\’s never shown up,but I\’ve also let them know and see my script. However my primary doctor tested me two weeks ago sent it to lab and found it…she was upset because I\’d went to another doctor/dietician to get them as she refused to after a script of one month.She told me if I tested positive again she\’d stop all my other meds which are all non narcotic.Im very upset as she is trying to tell me I cannot see her if I see other doctors.Shes only a practicioner.Is she breaking medical laws?I pay all out of pocket to see my dietician.

    • Hi April – Your doctor may be concerned about the possibility of dangerous drug combinations if you’re receiving prescription medications from different physicians, especially when she specifically refused to prescribe phentermine. She may also be worried that you’re still taking phentermine if she had a specific reason for halting your prescription. So, we would suggest speaking with her about your phentermine use (both why she doesn’t want you to take it and why you do want to take it) to see if you can reach some sort of mutual understanding. Best wishes!
      Rachel, phentermine.com

  32. I recall years ago when I was under a doctor\’s supervision while taking Phentermine, I was unexpectedly rushed to the hospital due to an allergic reaction from an insect bite (not Phentermine!). My urinalysis tested \”positive\” for the drug and I recall the nurse telling me \”we have a problem\” meaning the Phentermine had shown up in the test. She questioned me and I told her I was taking it under a doctor\’s care. She didn\’t go any further by asking me to provide proof from the doctor, but I supposed she could have. So I would say if you are taking it, yes it will be a \”red flag\” to a prospective employer unless you prove it is legal. If found illegally, you probably could be fined or arrested. I know it sounds ridiculous, but the law is the law. So if you take a drug test, be aware the test WILL find this substance.

  33. I don’t see why there would be a problem with pre-employment drug screening if the medication is prescribed. I was screened for my current job and many times prior as required by all facilities when I was going to college and never had a problem. They used a 12-panel drug screen. I was taking phentermine, tramadol, and ambien (not all at the same time). I never received a call to verify my scripts but now there is registry for all controlled substances that a provider can access to determine what meds have been prescribed, by which doctor, which pharmacy filled the script on what dates, and the exact dose prescribed of all meds filled in the past 12 months. I work in healthcare and have easily verified scripts with this system to determine if the patient has the med prescribed or is using illegally.

  34. I was taking Phentermine 37.5 , for about 1 week ( skipping 1 or 2 days through out ) . I then took a urine test , which tests for 17 different illegal drugs and parscription.medsp .
    I hadn\’t taken the Phentermine from Sunday @ 11 am, to Wednesday at 4 pm …. So, about 77 hours off them. I\’m worried , Yes I have a script but I do not want it to show up or have to explain. I obviously will, if needed . Amphetamines are cleared from urine, in about 3 days . Is there a difference with the Phentermine and the amphetamine that way ( I\’ve saw it saw \” 4-7 days for phen\” ) .

    • Hi!
      Phentermine can indeed take up to 7 days to flush out of your system. There’s no hard, fast rule about how long it takes because it varies, depending on factors such as time under phentermine treatment, age, etc.

      We hope everything turns out right!



  35. I was taking Phentermine 37.5mg for about a month or 2. Since then I was put on Probation and they asked me to stop taking it due to a positive amphetamine panel in my urine. I havent been taking it for a whole month now and its still showing up in my urine. This past week my amphetamine level even spiked up and I honestly haven\’t taken not one dose. Why is it that this is happening?

  36. I just need to know if this 30 mg phentermine will show up in a hair test as I don’t have a prescription For it I been taking one a day to lose weight for about two weeks and I just got called today for a job on a rig and they do hair test now I’m worried

    • Hi Rudy. Yes, it’s very possible that the phentermine would show up in a hair test if you have been taking it everyday for 2 weeks.
      Rachel, phentermine.com

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