More than 90% of all US prescriptions are filled with generic drugs — yet millions of Americans still wonder: is the generic really the same? Is it safe? This complete 2026 guide answers that question definitively: what the FDA actually checks before approving a generic, why the real average blood-level difference is less than 4%, the one category of drugs where extra caution is warranted, the 7 red flags of fake generics online, why Indian WHO-GMP manufacturers supply the US