Metformin over the counter: Why it requires a script and how to get one safely
Dr. Susan Carter, MD: Endocrinologist & Longevity Expert
Dec 08, 2025 · 11 min read
Metformin is prescription-only in the U.S., Canada, and the U.K. because it alters mitochondrial energy metabolism and relies on kidney clearance, so reduced renal function can increase the risk of lactic acidosis (dangerously high blood acidity). If you’re pursuing it for weight management or longevity, here’s how clinicians evaluate labs and prescribe it safely through ...