Phentermine is a prescription drug approved by the Food and Drug Administration (FDA) for weight loss because it decreases your appetite. It acts as a central nervous system stimulant, which can increase your heart rate and blood pressure, cause muscles to contract, and make you feel more alert.

Phentermine is similar in nature to an amphetamine. Because of this, it can produce a “false-positive screen” for amphetamine on a urinalysis test. However, it will not confirm positive for amphetamine or be reported as positive through the military drug testing program. However, phentermine is a Schedule IV drug. (Phentermine is on the Drug Enforcement Administration’s list of controlled substances.) That means phentermine can be obtained legally only by prescription. (There is some clever marketing online where it appears you are buying Phentermine, but actually it is a dietary supplement product.)

Please also see the OPSS article about prescription weight-loss medications, which includes links to service-specific policies regarding Phentermine and other prescription weight-loss medications. For more information on drug testing, please see OPSS’s “Drug testing and dietary supplements.” We also suggest reading the MedlinePlus web page about Phentermine, which includes information about side effects, dosage, etc.

Updated 26 February 2019