What medications cause weight gain?
Last updated September 3, 2026.
Weight gain is pharmacology, not willpower failure: MedlinePlus lists it among the most common antidepressant side effects, and steroids, antipsychotics, insulin, some beta-blockers, and seizure medicines carry it too. Mechanisms range from appetite increase to fluid retention. Never stop the drug over the scale; instead, track whether the gain tracks the start date, and ask the prescriber about weight-friendlier alternatives within the same family, which usually exist. Rapid gain over weeks deserves a prompt appointment; gradual gain is managed with diet, movement, and sleep alongside any medication adjustment.
What to do
- Track the timeline; gain tracking the start date is the tell.
- Never stop the drug abruptly.
- Ask about weight-friendlier alternatives in the same family.
- Get seen promptly for rapid gain over a few weeks.
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