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.

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 can vary depending on the person, amphetamines clear from the system within 72 hours. So, phentermine should not be detectable in the body after a period of around three or four days.

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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25 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.

  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.

  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.

  5. I have been taking Phentermine up until 5-7 days before I see my doctor. I do this simply to avoid hearing the “pep” talk from my doctor about the medication’s long term effects it can have on my body. I have been taking urine screenings approximately 5-7 days after I quit taking the Phentermine & its still showing up in a urine screening that it is in my system. If it is supposed to be out of a persons system in 72 hours in most cases, how is it still in my system after 7 days? How is it showing up on a lab urine screening in a healthy person after an extra 4 days than the standard of 3 days?

    • Hi LoudJMomma,
      As you say, in most cases, 72 hours is long enough for phentermine to leave the system. However, everyone metabolizes drugs differently so it would seem that it remains present in your system for longer than the average person. If you have been taking it for a long time it may be due to this, or other factors such as your body weight, height, the dosage you’re taking etc.
      Sally, phentermine.com

      • What if I took one pill it for one day (Monday) and I recently receive a phone to do a drug test on a friday for a new job offer!. The test its on friday…would it appear on the test? should I be worried. Thanks

        • Hi Yolanda,
          In most cases the phentermine should be out of your system if you haven’t taken it for three days. However, it’s not guaranteed, since it depends on how your body metabolizes phentermine, so you should be prepared to show your prescription for proof in case there are signs of what appears to be amphetamines in your system.
          Sally, phentermine.com

  6. 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

  7. 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

  8. 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

  9. 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.

  10. 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

  11. 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..

  12. 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.

  13. 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

  14. 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

  15. 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

  16. 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.

  17. 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,
      After five days without phentermine it is quite likely that it will be out of your system before you have the urine test. However, because of the way we all metabolize drugs differently, it may still be in your system and could give a false positive reading for amphetamines on the urine test.
      Sally, phentermine.com

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