The type of bacteria causing the infection will determine what type of antibiotic you’ll need. Different types of antibiotics have different ways of attacking bacteria. Your dentist will choose an antibiotic that can successfully eliminate your infection. Antibiotics such as amoxicillin and penicillin are commonly used to help treat tooth infections. Be sure to tell your dentist if you’re allergic to penicillin (if you do not know, ask your doctor). An alternative to penicillin is erythromycin and can be prescribed in its place. Information about dosage, frequency and how to take the medication will be given to you by your local pharmacist. However, you will typically need to take antibiotics for about a week and be sure to use the entire prescription to ensure the infection is completely gone.