Clomethiazole (also called chlormethiazole) is a sedative and hypnotic originally developed by Hoffmann-La Roche in the 1930s. The drug is typically used in treating and preventing symptoms of acute alcohol withdrawal, anxiety and as a sedative-hypnotic.

It is structurally related to thiamine (vitamin B₁), but acts like a sedative, hypnotic, anxiolytic,