Phentermine
A stimulant appetite suppressant approved for short-term weight loss — the most-prescribed weight drug of the pre-GLP-1 era.
Phentermine has suppressed appetites since 1959: a sympathomimetic stimulant that quiets hunger through norepinephrine release. It is inexpensive, generic, and FDA-approved — but only for short-term use (generally up to 12 weeks), with scheduling as a controlled substance and cautions around blood pressure, heart rate, and stimulant side effects like insomnia and jitteriness.
Typical results run 3–7% of body weight over its short window, and weight commonly returns when it stops. Against modern GLP-1 therapy — larger averages, chronic-use approval, metabolic benefits — phentermine now serves niches: budget constraints, bridging, or combination in Qsymia. Its era as the default answer is over.
This glossary entry is general information, not medical advice, and is written to be consistent with FDA prescribing information and primary trial publications as of its last review. Always consult a licensed healthcare provider for personal medical decisions.
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