Amoxicillin
Broad-spectrum β-lactam penicillin-class antibiotic. WHO Essential Medicines, one of the most prescribed antibiotics worldwide. Standard first-line for otitis media, sinusitis, pneumonia, UTI, dental prophylaxis, and H. pylori eradication.
WHAT IS AMOXICILLIN?
Detailed overview
Amoxicillin is an aminopenicillin, an orally well-absorbed derivative of ampicillin, developed by Beecham in 1972 (Amoxil). As a β-lactam antibiotic, it inhibits bacterial cell wall transpeptidase (PBP, penicillin-binding protein), disrupting peptidoglycan cross-linking and causing bacterial lysis. Spectrum: Gram-positive (Streptococcus, Enterococcus), Gram-negative (H. influenzae, E. coli, H. pylori, Helicobacter, Borrelia). Resistant to β-lactamase-producing bacteria (Staphylococcus, Klebsiella, anaerobes), so often combined with clavulanic acid (Augmentin) to broaden spectrum. On WHO Essential Medicines, regulated prescription in EU/USA under antibiotic resistance context.
ATC code
J01CA04
Prescription
Prescription only (Rx), antibiotic stewardship
Mechanism
β-lactam, PBP transpeptidase inhibitor, bactericidal
Half-life
1-1.5 h (renal function-dependent)
Onset
1-2 h (plasma peak), 24-72 h (clinical response)
Data console
Lab data
Safety
Side effects, stop signs, contraindications
Side effects · 7
- Diarrhea and antibiotic-associated gut flora disruption (about 10%); rarely severe Clostridioides difficile colitis with bloody stool, cramps and fever.
- Hypersensitivity reactions: maculopapular rash, urticaria; rarely severe, life-threatening anaphylaxis (<0.05%), especially with IgE-mediated penicillin allergy.
- Nausea, vomiting, abdominal discomfort, loss of appetite, taste disturbance.
- Candida superinfection (vaginal or oral thrush) due to disruption of normal flora.
- Severe rare skin reactions: Stevens-Johnson syndrome, toxic epidermal necrolysis (TEN), DRESS, acute generalized exanthematous pustulosis (AGEP) – require immediate discontinuation.
- Acute interstitial nephritis and, at high doses, crystalluria (preventable with adequate hydration); rarely reversible transaminase elevation, cholestatic jaundice (more often with the clavulanate combination).
- In mononucleosis (EBV) infection a maculopapular rash appears almost always (80-95%) – this is NOT a true penicillin allergy.
Contraindications · 3
- Known penicillin or β-lactam allergy (anaphylaxis history)
- Severe hypersensitivity (Stevens-Johnson, TEN, DRESS) history
- Mononucleosis (EBV) infection – amoxicillin causes maculopapular rash in 80-95%
Related Pharmaceuticals
Same therapeutic category
Studies
Related research and clinical findings
Antibiotic prescribing patterns and resistance: Amoxicillin in community-acquired infections
Costelloe C, Metcalfe C, Lovering A et al.
Amoxicillin vs amoxicillin-clavulanate for acute otitis media in children
Hoberman A, Paradise JL, Rockette HE et al.
Effectiveness of amoxicillin and amoxicillin-clavulanate for the treatment of community-acquired pneumonia in adults and children: a systematic review and meta-analysis.
Potter-Schwartz L, Swe MM, Sharland M
Non-Bismuth Quadruple Concomitant Treatment for Helicobacter pylori Eradication: A Systematic Review and Meta-Analysis.
Parra P, Nyssen OP, Gisbert JP
Prevention of infective endocarditis: AHA scientific statement
Wilson W, Taubert KA, Gewitz M et al.
Amoxicillin for Lyme disease in children and pregnancy
Lantos PM, Rumbaugh J, Bockenstedt LK et al.
Antibiotic stewardship and WHO AWaRe classification
Sharland M, Pulcini C, Harbarth S et al.
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Have a question about Amoxicillin?
Educational drug info from official sources (PubMed, FDA, EMA). Does NOT replace medical consultation or the SmPC. Talk to your doctor!
The information here is for educational and scientific purposes only. Medication use requires medical consultation and a prescription. The indications, dose ranges, and side effects listed here do NOT replace the official Summary of Product Characteristics (SmPC) or consultation with a physician. Do not start or stop any medication on your own. In an emergency, call your local emergency number.