Amoxicillin is a type of penicillin, an antibiotic that doctors prescribe to treat bacterial infections. It takes effect quickly, but it may take 24 to 72 hours to see an improvement in your symptoms.

When to Use and Avoid Antibiotics and Other Treatments to Try Medically reviewed by Kimberly Brown, MD Sinus infections that do not clear up on their own may need treatment with antibiotics. Common ...