Antibiotics & Prophylaxis in Dental Practice

Antibiotic classes

Class (examples)	Mechanism	Dental notes
Penicillins (penicillin VK, amoxicillin, amoxicillin–clavulanate)	Cell wall (bind PBPs); bactericidal	First choice for most odontogenic infections; clavulanate blocks β-lactamase
Cephalosporins (cephalexin)	Cell wall; bactericidal	Avoid if penicillin allergy involved anaphylaxis, angioedema or hives
Macrolides (azithromycin, clarithromycin, erythromycin)	50S ribosome; bacteriostatic	QT prolongation; clarithromycin and erythromycin inhibit CYP3A4
Clindamycin	50S ribosome	High risk of C. difficile infection; removed from AHA endocarditis prophylaxis (2021)
Tetracyclines (doxycycline)	30S ribosome; bacteriostatic	Chelated by calcium, iron, antacids; tooth staining during tooth formation (short doxycycline courses are now considered acceptable in children); photosensitivity; low-dose doxycycline 20 mg inhibits collagenase
Metronidazole	DNA damage in anaerobes	Disulfiram-like reaction with alcohol; raises INR with warfarin; anaerobic coverage (often added to amoxicillin)

Situation	Adult	Child
Oral	Amoxicillin 2 g	50 mg/kg
Penicillin allergy	Cephalexin 2 g (if no anaphylaxis, angioedema or hives with penicillin), or azithromycin or clarithromycin 500 mg, or doxycycline 100 mg	Cephalexin 50 mg/kg; azithromycin or clarithromycin 15 mg/kg; doxycycline 2.2 mg/kg (under 45 kg)
Cannot take oral	Ampicillin 2 g IM/IV, or cefazolin or ceftriaxone 1 g IM/IV	Ampicillin 50 mg/kg; cefazolin or ceftriaxone 50 mg/kg

Who: prosthetic valve or prosthetic valve-repair material; previous infective endocarditis; unrepaired cyanotic congenital heart disease; repaired congenital heart disease with prosthetic material in the first 6 months or with residual defects next to it; cardiac transplant with valvulopathy.
What: procedures that manipulate gingival tissue or the periapical region or perforate the oral mucosa. Not needed for routine injections through noninfected tissue, radiographs, orthodontic adjustments or shedding primary teeth.
Prosthetic joints: the ADA (2015) states prophylaxis is generally not recommended; defer to the orthopedic surgeon's documented recommendation for specific patients.

Pulpitis, apical periodontitis or a localized abscess without systemic signs: definitive dental treatment (pulpectomy, incision and drainage, extraction); antibiotics are not recommended.
With systemic involvement (fever, malaise, spreading swelling, lymphadenopathy): definitive treatment plus amoxicillin 500 mg three times daily (or penicillin VK 500 mg four times daily) for 3–7 days; reassess at 3 days and stop 24 hours after symptoms resolve.
Penicillin allergy: cephalexin (if no anaphylaxis history) or azithromycin; clindamycin only when others are unsuitable.

Prescribing clindamycin for endocarditis prophylaxis: the AHA removed it in 2021.
Giving antibiotics for irreversible pulpitis without systemic signs.
Giving cephalexin to a patient whose penicillin allergy was anaphylaxis.
Forgetting the metronidazole–alcohol and metronidazole–warfarin interactions.

Pick an answer to see right away whether it is correct and why.

A patient with a prosthetic aortic valve and no allergies is having scaling. The prophylaxis regimen is:
A patient with a prosthetic valve had anaphylaxis to penicillin. Which prophylaxis option is appropriate?
A healthy adult has symptomatic irreversible pulpitis with no swelling or fever. Antibiotics are:
Which antibiotic causes a disulfiram-like reaction with alcohol?
Doxycycline absorption is reduced most by taking it with:

0 of 5 answered

Answer key: 1 A · 2 A · 3 B · 4 C · 5 C

Dental School Map · Original study material, written and checked by our team; always confirm clinical decisions against current guidelines.