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.
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Amoxicillin vs Ciprofloxacin vs DoxycyclineWHAT 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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Educational drug info from official sources (PubMed, FDA, EMA). Does NOT replace medical consultation or the SmPC. Talk to your doctor!
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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.