Phentermine is a prescription medication used as a short-term treatment for weight loss. It is classified as an appetite suppressant and belongs to a class of drugs called sympathomimetic amines. Phentermine works by affecting certain neurotransmitters in the brain, specifically norepinephrine, which helps reduce appetite and increase feelings of fullness.

Phentermine is typically prescribed for individuals who are struggling with obesity and have not been successful with other weight loss methods, such as diet and exercise alone. It is meant to be used as part of a comprehensive weight loss program that includes lifestyle changes.