Penicillins · Anti-infectives
Amoxicillin
amoxicillin-clavulanate (with clavulanic acid) · Amoxil® · Clavulin (with clavulanate)®(brand names vary by market)
The everyday aminopenicillin: reliable gram-positive and respiratory coverage, gentle on almost everyone.
Also: tablet, oral liquid
Mechanism
Beta-lactam: binds penicillin-binding proteins, blocking cell-wall cross-linking. Bactericidal, time-dependent killing.
Indications
- Community-acquired pneumonia (component)
- Otitis media, sinusitis, pharyngitis (selected)
- Dental infections
- H. pylori regimens
Formulations
Dosing concepts
Time-dependent
Efficacy tracks time above MIC, which is why the interval matters as much as the amount.
Renal function
Renally cleared; intervals stretch in significant impairment.
Concepts, not prescribing instructions. Practice numbers live in current references and local protocols.
Pharmacokinetics
- Bioavailability
- ~75-90%
- Half-life
- ~1 h
- Elimination
- renal
Adverse effects
- Diarrhea, nauseacommon
- Rash (especially with EBV)commonA maculopapular ampicillin rash is not the same as penicillin allergy.
- Anaphylaxis in true IgE allergyserious
- C. difficile colitisserious
Contraindications & precautions
Contraindications
- Documented severe penicillin hypersensitivity
Precautions
- Allergy histories deserve interrogation. Most recorded 'penicillin allergies' are not
- Infectious mononucleosis (rash)
Interactions
Monitoring
Clinical response by 48-72 h
The reassessment moment every antibiotic course owes
Diarrhea
C. difficile risk with any antibiotic
Counselling points
- Space doses as evenly as you can and finish the course as prescribed.
- A little stomach upset is common; severe watery diarrhea is not: call.
- If you are on warfarin, mention this antibiotic; INR can drift.
Clinical pearls
- Interrogating a vague penicillin-allergy label is one of the highest-value acts in antimicrobial stewardship.
References & review
- Amoxicillin product monograph (consult the current version for your market) (monograph)
- Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed. (reference-work)
Last reviewed 2026-08-15 · jurisdiction: global · drug information changes; verify against current references before practice use.