Will Phentermine Show Up On A Drug Test?

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 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 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, identify and help employees with drug and/or alcohol problems, protect the general public, and comply with employment laws and regulations.

The most common drug test method is urinalysis, which 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 ensure 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 your phentermine, the result should be declared 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 Your System?

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.

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, you may prefer to stop taking phentermine for a few 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 worrying about failing an employment drug test.

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

Frequently Asked Questions

What is the half-life of phentermine?

The half-life of phentermine is around 16 to 31 hours. However, the drug’s half-life will vary depending on each person’s metabolism and the pH of their urine. Generally, this means that phentermine will no longer be detected in the urine 4 to 7 days after the last dose was taken. However, the detection period could be longer if phentermine has been taken at a high dose or for a long time.

What does phentermine show up as on a drug test?

Phentermine can show up on a drug test as a false positive for amphetamine. This is because, despite being different drugs, phentermine and amphetamine have a similar chemical structure. If you can provide your employer with evidence that phentermine has been prescribed for you, then a positive result for amphetamine should be declared a false positive.

Can I get fired for taking phentermine?

Phentermine is not illegal, but it is a controlled substance. This means it should only be taken if you have a prescription. If you take phentermine without a prescription, your employer may view this as illegal usage of the drug. This could result in disciplinary action.

Will phentermine show up on urinalysis?

If you have taken phentermine, urinalysis performed to screen for drugs may give a false-positive result for amphetamine. This is because of the chemical similarities between the two drugs. However, if you can provide evidence that a doctor has prescribed phentermine for you, the result should be declared a false positive.

How can I pass a urine drug test for phentermine?

Taking phentermine may trigger a false-positive result for amphetamine use on urine drug tests. Therefore, if you take phentermine, in some cases, it is advisable to provide your employer with a copy of your prescription before you take the drug test. This proves that you are taking a controlled substance in the manner it was prescribed, avoiding the need for an explanation if the test should return a positive result.

How long does Labcorp take to provide urine results?

Labcorp aims to complete urine testing within a few days, but result delivery times for more complex tests may take longer. However, all tests are usually completed within two weeks. If you request testing as an individual, your results can be accessed by logging into your Labcorp patient portal account. If your employer requests a drug test, the results will be sent directly to them.

Will Labcorp call me if I fail a drug test?

Labcorp will not call you if you fail a drug test. A drug test that detects an illegal substance will either be reported on your patient portal account or sent directly to your employer. However, Labcorp may call you if they require you to provide a second urine sample, for example, if the first sample was contaminated or invalid for another reason.

How long will phentermine be detectable on a hair drug test?

When comparing blood, urine, and hair drug testing, phentermine remains detectable for the longest period of time in the hair. Phentermine may still be detected in a hair follicle even if you have not taken phentermine for a month or longer.

Does phentermine show up on a 10 panel drug test?

Testing for amphetamine forms part of a 10-panel drug test, meaning that phentermine may be erroneously categorized as amphetamine as part of the test. Amphetamine and the other drugs screened for in a 10-panel test are chosen as they are the most commonly misused drugs in the USA. The panel also includes cannabis, cocaine, barbiturates, opioids, benzodiazepines, phencyclidine (PCP), methaqualone, methadone, and propoxyphene.

Is Adipex a narcotic?

Adipex is a brand name for phentermine. In countries including France, Adipex is considered to be a narcotic. However, in the USA, generic and branded phentermine belongs to a group of drugs called sympathomimetics or CNS stimulants.

Is phentermine meth?

Phentermine is an isomer of methamphetamine or meth. This means that the two substances are made up of the same atoms, but the atoms are arranged completely differently. This difference is very important, as it gives the drugs different properties. Despite sharing the same group of atoms, the structure of phentermine makes it far less potent than methamphetamine.

Will Topamax show up on a drug test?

Topamax is the brand name for topiramate. Most drug tests do not test for topiramate or its metabolites, so it is unlikely that topiramate or Topamax would show up on drug testing.

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137 Comments

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

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

  2. 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?

          1. Hi Dakota,

            Yes, phentermine could be potentially detected through saliva. 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.

            Rebeca, Phentermine.com

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

  4. 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?

    1. 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.

  5. 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.

    1. Were you dismissed?! I have an appointment with pain management tomorrow, I had no idea this could get me in trouble!

  6. 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!

  7. 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?

  8. 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.

  9. 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. 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. 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?

    1. 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. 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. I stopped phentermine 2 months ago exactly. I have a hair follicle on Monday! The 5 panel hair follicle will I fail?

      1. Hi Amanda,

        With evidence of your past prescription, the result should be declared as negative. Also, depending on the type of test, it might not even show up at all.

        Rebeca, Phentermine.com

    1. 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

  12. If I took adipex 37.5 Friday morning and did not take it again and had drug screen on Tuesday will it show up

  13. Hello, I take my phentermine as prescribed. I drive professionally and I’ve had no problems doing my job and they don’t drug test. However I’m going to be tested for a new driving position delivering plants and flowers. Do you know if I will be accepted with my prescription and a possible false positive? I want to tell my boss but I’m afraid that it will disqualify me. I could stop taking the medication but I also don’t want to hinder my progress because soon I’ll be on my two month break from the drug. I think that I’m on it 3 months and then off for 2 months.

    1. Hi Karen,

      Thank you for reaching out. 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 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.

      We hope this helps! Good luck in your job interview!

      Rebeca, Phentermine.com

  14. I am taking Phetermine in combination with phendimetrizene,had take urine drug screen,what happens if comes back positive for amphetamines,I prove I have script for phetermine,but MRO doesn’t accept explanation ,meaning could say Phetermine won’t cause positive?anything I can do?i don’t wanna lose my job

    1. Hi Brian,

      With evidence of your prescription from the doctor who prescribed you phentermine, then the result should be declared as negative. Also, depending on the type of test, it might not even show up at all. Just make sure you have your prescription at hand.

      Rebeca, Phentermine.com

  15. Hola, tuve un test de droga pre-empleo el Martes 21/07/20; tomo Phentermine 37.5 mg. Pero la última píldora que me tomé fue el Sábado 18… es posible que salga positiva en la prueba?
    Me tomaron de orina y 6 paneles de sangre, pero no me dijeron cuáles!!!

    1. Hola Guadalupe,

      Sí es probable que salga un falso positivo pero no es completamente seguro. Depende de la prueba.

      En caso de que salga positivo, siempre tienes la opción de mostrar tu receta médica y el resultado debe declararse como negativo.

      Mucha suerte,

      Rebeca, Phentermine.com

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