Home / Blog / Phentermine and Interactions: Phentermine and Drug Test

Phentermine and Drug Test

Phentermine and Drug Test

phentermine and drug testingPhentermine is a Schedule IV controlled substance under the United States Controlled Substances Act. This means that it has some potential for abuse, which can lead to physical or psychological dependence, and cannot be dispensed without a prescription. Phentermine has a similar pharmacology to amphetamines, which leads some users to worry about whether taking phentermine will interfere with routine drug screenings. Fortunately, the majority of users won’t have to worry, and will be able to pass their screenings without a problem.


Phentermine vs. Amphetamines

Phentermine is a sympathomimetic amine. This means that it mimics the actions of natural transmitter chemicals within the sympathetic nervous system. It can do things like suppress appetite, raise your heart rate, and increase your blood pressure. This is similar to the effects of amphetamines, though amphetamines have a slightly different action. In general, amphetamines have a stronger action than phentermine. Many of them are considered Schedule II controlled substances, and are subject to much stricter regulations than phentermine.


Phentermine and Oil-Emersion Drug Tests

Most drug tests do not screen for sympathomimetic amines, like phentermine. This means that the majority of users will not have phentermine show up in their system. That said, some very high-end drug tests, like oil-emersion tests, can detect phentermine. This will produce a positive result on your drug screening.


If you want to be on the safe side, do not take a drug test while you are on phentermine. Phentermine can be expressed in urine for between two and four days, depending on how quickly your body metabolizes it.


What to Do if You Test Positive for Phentermine?

Since phentermine is a Schedule IV controlled substance, it is not legal to take it without a prescription. Therefore, honesty is always the best policy- when you go to take a drug test, bring:

  • A copy of your prescription.
  • A note from your doctor.
  • Your doctor’s contact information.

This will enable you to verify that you’re taking a legal prescription. If you have your prescription filled online, make sure to inform the technicians in charge of testing you. They may need to contact your doctor in order to make sure that your prescription is legitimate.

If you do not have a prescription for phentermine, you should not be taking it. In addition to being a Schedule IV controlled substance, phentermine can produce dangerous side effects in certain people. It is very important that you have a full examination and a doctor’s approval before you begin using this or any other prescription medication.



Though phentermine is not the same as an amphetamine, it is similar enough to cause your drug test results to be flagged as positive for amphetamine use. Most laboratories will run two or three different analyses in order to confirm that the positive result is actually phentermine, and not amphetamines. The most important thing you can do is to be completely upfront about your phentermine use, and be able to produce all of the documentation you have relating to your prescription.


© 2012, Phentermine 37.5. All rights reserved. Do not copy! On republishing this post you must provide link back to original post.


Write a comment:


Your email address will not be published.

Copyright © 2009 - 2013
Contacts | FAQs | Sitemap |