How Long does It Take for Antibiotics to Work?

It depends on the antibiotic, how it is administered, and what you are taking it for. For something simple like a mild infection it usually starts working within two days. For complex things like a severe infection or a bacterial infection it can take up to a week. It is very important to continue to take antibiotics until the prescription is gone (usually about 12 to 14 days) because even though the symptoms may be gone the infection itself might not be totally finished.