Pharmacology Knowledge organiser
Antibiotic prescribing and prophylaxis in dentistry
Antibiotics do not treat a dental abscess; drainage and removal of the cause do. Antibiotics are added only where there is systemic involvement, spreading infection or a patient at particular risk, and the first-line choices, doses and interactions are precisely defined in UK guidance.
The rule
SDCEP Drug Prescribing for Dentistry (3rd edition, 2016) and the FGDP antimicrobial prescribing guidance (2020): for acute dentoalveolar infection with systemic involvement or spreading infection, first line is phenoxymethylpenicillin 500 mg four times daily or amoxicillin 500 mg three times daily for up to five days, reviewed at two to three days; metronidazole 400 mg three times daily for up to five days for penicillin allergy or for predominantly anaerobic infections such as pericoronitis and necrotising gingivitis; in severe infection amoxicillin and metronidazole may be combined; clarithromycin is the alternative macrolide. NICE clinical guideline 64 (2008, amended 2016): antibiotic prophylaxis against infective endocarditis is not recommended routinely for dental procedures; SDCEP implementation advice (2018) describes a small sub-group of patients for whom the cardiologist may advise prophylaxis, in which case amoxicillin 3 g orally 60 minutes before the procedure, or clindamycin 600 mg for penicillin allergy, is used.
Exam trap
Metronidazole interactions: alcohol (disulfiram-like reaction), warfarin (raised INR), lithium (toxicity).
Show distinctions and misconceptionsHide
- Localised swelling with a drainable abscess and no systemic upset: drain (through the tooth or by incision), remove the cause, no antibiotic. Fever, malaise, lymphadenopathy, trismus or cellulitis: antibiotic in addition to drainage. Airway compromise or spreading facial cellulitis: urgent hospital referral.
- Metronidazole is active against obligate anaerobes only; it is the drug for pericoronitis and necrotising periodontal disease and the alternative in penicillin allergy.
- Believing that antibiotics are appropriate for irreversible pulpitis. They have no effect on pulpal pain; the treatment is pulp extirpation or extraction.