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Will Phentermine Show Up On A Drug Test?

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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.

[infographic-share-popup post=”5844″ share-text=”Worried about phentermine showing up on your drug test for work or school? Click here to learn more!”][/infographic-share-popup]

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.

97 thoughts on “Will Phentermine Show Up On A Drug Test?”

  1. Avatar

    I took 1/2 of a phentermine this morning & have a drug screen today or tomorrow. Will it show eventhough it was just half?

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

  2. Avatar

    Hello i took 1/2 a phentermine on saturday 7 am and had a drug test wednesday 11 am will this show on my drug screening?

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    I have been on Phentermine for a while now. I took a hair test and it came back positive for meth. I have never taken meth in my life nor any other illegal drug. I stopped taken phentermine. I took a mouth swab and UA for Cps both were negative. I took another hair test and it’s negative. Could the pill phentermine came back positive?

    1. Avatar

      Hi Joella! Yes, phentermine can cause a false-positive for amphetamines (meth) due to the substances’ similar chemical structures.
      Rachel, phentermine.com

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    I took a random urine drug test and and I failed for amphetamines. MRO called 3 weeks later to ask if I take prescriptions for this and I told them that I do not take amphetamines, but I do take Phentermine. MRO then proceeded to tell me that it would not cause me to fail for amphetamines. What can or should I do?

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      Yes it can cause you to fail for amphetimenes. It is chemically similar to an amphetimene. They can do a confirmatory test to show exactly what you took. Ask them for that test if your phentermine is legally prescribed.

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    Hello I took Phentermine diet pill on Wednesday morning and had a mouth swab drug test Friday will it show up? Please help kinda freaking out because I don’t want to be dismissed from pain management.

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    I been on phentermine 37.5 since November 2018. I just to drug test and it came back positive for COC! I have took other drug test due to my job which they come up randomly and never produce a positive result before taking this medicine!

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    A 10 panel UA tests separately for Amphetamine AND Methamphetamine. Is it possible for Phentermine to create a false positive for both on a 10 panel test?

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    Hi- I have a job interview on Monday (7/15) at 3pm and my last phentermine pill was at 7am thursday at 7am (7/11). The pill is 30mg. They will be conducting a mouth swab test. I plan not to take any more phentermine. Will it show up on the mouth swab test? I took it for 18 days and this will be 104 hours since taking phentermine I do have a prescription for it.

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    I have to take a drug test for new employment but I’ve been on Phentermine for a month now my question is what do I do should I tell them? I really don’t won’t to lose this opportunity and I also haven’t taken any in 2 days but I am just scared

    1. Avatar

      Hi Nina 🙂 Phentermine is legal as long as you have a valid prescription, so many employers will accept a positive result as long as you bring the current prescription (depending on the prospective industry and job functions, of course). Good luck!
      Rachel, phentermine.com

  10. Avatar

    I have been on it for a month and a half just took a drug test and it tested positive for meth somedays I take 1 and a half but not on the day of the test will I pass?

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      Hi TJ! Phentermine typically stays in the system (and is detectable in urine) for about 4-7 days, and sometimes longer if you’ve been taking it for a long time or at high doses. So, if you’ve taken phentermine in the last week, it’s likely that it will show up on the drug screen. We’d recommend that you go prepared with your prescription in-hand, just in case.
      Best regards,
      Rachel, Phentermine.com

  11. Avatar

    My brother recommended I might like this blog. He was once entirely right.
    This submit truly made my day. You cann’t consider just how much time I had spent for this info!
    Thank you!

    1. Avatar

      Hi James! Yes, it’s possible that the medication will show up on the drug screen. Be prepared to show your prescription just in case.
      Sally, phentermine.com

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