Antibiotics are antimicrobial drugs used to treat infections when the immune system of the host is unable to overcome infection and eliminate microorganisms. In endodontic therapy, the use of antibiotics may be systemic, local, and prophylactic. Most of the odontogenic infections are confined within the tooth and can be successfully treated locally: by trepanation of the tooth, by incision and by establishing drainage or tooth extraction. The systemic use of antibiotics in the treatment of odontogenic inflammation is only adjuvant in situations where it is necessary to prevent systemic spread of infection. In addition to the primary therapy administered, antibiotics will be systematically prescribed in the case of elevated body temperature, regional lymphadenitis, spread of infection through the cortical bone and through the soft tissues. Topical application of antibiotics is indicated in regenerative endodontic procedures and in replantation of avulsed teeth, where systemic antibiotics should also be considered. Amoxicillin, by itself or in combination with clavulanic acid, is the most common antibiotic used to treat endodontic infection. In the case of confirmed penicillin allergy, the drug of choice is clindamycin. In local therapy, on the other hand, tetracycline is the most common. Antibiotic prophylaxis is indicated in medically compromised patients who are more likely to develop complications from odontogenic infection, i.e. patients with uncontrolled systemic diseases, with supressed immunity, patients with prosthetic cardiac valves, infective endocarditis, and patients with recent prosthetic joint replacement. The prophylaxis is applied in a single dose 30-60 minutes prior to invasive dental procedures.