What's the difference between generic and brand-name drugs?

The FDA's answer is flat: generic drugs are FDA-approved copies containing the same active ingredient, in the same strength, dosage form, and route, working the same way in the body as the brand - and held to the same scientific quality standards. To be approved, a generic must prove bioequivalence: it delivers the same amount of active drug to your bloodstream over the same time course as the brand, within tight statistical limits. So what actually differs? The name, the look (trademark law forbids generics from copying the brand's shape and color), the inactive ingredients (fillers, dyes - rarely relevant, occasionally an allergy issue), and the price: generics skip the decade of original clinical trials, which is why they cost a fraction. When brand might matter: a handful of narrow-therapeutic-index drugs - levothyroxine, warfarin, some seizure medicines - where tiny blood-level swings matter; for those, doctors often say pick one manufacturer and stick with it, brand or generic, because consistency is the goal. And if a switch ever feels different, say so - the answer is usually the look or the fillers, but the conversation is free. Pymander is a free AI doctor, 24/7 by text, that can help you think through a switch.