Amoxicillin
AMOXIL
Pronunciation: a-mox-i-SIL-in
“A Moxy ceiling”
Β lactam ring → the defining structure of penicillins and cephalosporins
What it isAminopenicillin that inhibits penicillin-binding proteins and cell-wall synthesis; common respiratory and ear infections.
Why this oneUnlike ampicillin, reliable oral absorption plus pneumococcal activity makes it a first-line outpatient respiratory antibiotic.
What limits itBeta-lactamase producers escape it — that is what clavulanate is for. An EBV-associated rash does not by itself prove penicillin allergy.
Amoxicillin prescription history
Animated chart of estimated U.S. prescriptions per year, Penicillins (oral) (1955–2026). Amoxicillin enters in 1974.
FDA-approved for
- bacterial infections (~1974)
Principal riskHypersensitivity, including anaphylaxis
Classes and tags
Clinical profile
Legacy pregnancy categoryB
Defining liabilityAllergy, gastrointestinal effects and agent-specific renal, hepatic, hematologic or interaction risks.
FDA label
Read the full label on DailyMed ↗
NO BOXED WARNINGS
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| General infections | Adult | 750-1750 mg/day divided q8-12h | ||
| General infections | Pediatric >3 months | 20-45 mg/kg/day divided q8-12h | ||
| General infections | Neonates/infants <=3 months | up to 30 mg/kg/day divided q12h | 30 mg/kg/day | |
| H. pylori (triple therapy, with clarithromycin + lansoprazole) | Adult | 1 g BID x14 days | ||
| H. pylori (dual therapy, with lansoprazole) | Adult | 1 g TID x14 days |
Renal GFR 10-30 mL/min: 500 or 250 mg q12h; GFR <10 mL/min: 500 or 250 mg q24h; hemodialysis: 500 or 250 mg q24h plus a dose during and after dialysis; do not use 875 mg dose if GFR <30 mL/min.
Hepatic Undefined
Instructions
- Take at the start of a meal to minimize GI intolerance
- Continue at least 48-72 h after patient is asymptomatic; treat S. pyogenes infections at least 10 days
Available strengths
- cap 250, 500 mg
- tab 500, 875 mg
Contraindications
- Serious hypersensitivity (e.g., anaphylaxis, Stevens-Johnson syndrome) to beta-lactams (penicillins, cephalosporins)
Cautions
- Serious/fatal anaphylactic reactions
- Severe cutaneous adverse reactions (SCAR)
- Drug-induced enterocolitis syndrome (DIES)
- Clostridioides difficile-associated diarrhea (CDAD)
Adverse reactions
- Nausea
- Vomiting
- Diarrhea
- Rash
Pregnancy Mouse/rat reproduction studies at doses up to 2000 mg/kg showed no evidence of fetal harm; no adequate and well-controlled studies in pregnant women; use during pregnancy only if clearly needed.
Lactation Undefined
Cost
| Strength | #/mo | generic $/unit | CostPlus | |
|---|---|---|---|---|
| 500 mg | tab | per unit | $0.08/ea | offered |
| 875 mg | tab | per unit | $0.15/ea | offered |
| 250 mg | cap | per unit | $0.07/ea | offered |
| 500 mg | cap | per unit | $0.08/ea | offered |
Available combined with: Clavulanate (in AUGMENTIN) · amoxicillin / clavulanate
Generic entry1982
Open Amoxicillin in the interactive console ↗
Memory aids: interaction avatars
Open Amoxicillin in the interactive console ↗
Self-check
- Does an amoxicillin rash during EBV alone prove penicillin allergy?
No. - What bacterial defense defeats amoxicillin alone?
Beta-lactamase production.