amoxicillin
Drug class
Active ingredient: amoxicillin
- Penicillins with extended spectrumATC code: J01CASource: ATC
Allergy cross-reactivity
Class-level overall cross-reactivity (penicillin ↔ cephalosporin)
Risk level: Low
Basis: Class-wide (non-R1-matched pairs) — context group
Other active ingredients in the same group:
- ampicillin
- aztreonam
- benzylpenicillin
- cefadroxil
- cefalexin
- cefazolin
- cefepime
- cefixime
- cefotaxime
- ceftazidime
- ceftriaxone
- cefuroxime
- flucloxacillin
- piperacillin
Notes: Class-level overall cross-reactivity between penicillins and cephalosporins is LOW in modern data (~1-2%). The R1 side chain is the true determinant. Consult a specialist.
Source: https://www.ncbi.nlm.nih.gov/books/NBK459320/Amoxicillin ↔ Cefadroxil (identical R1)
Risk level: High
Basis: Identical amino R1 side chain
Other active ingredients in the same group:
- cefadroxilSubgroup: aminocephalosporin
Notes: Cefadroxil shares an identical R1 side chain with amoxicillin; reported cross-reactivity by DPT ~35-38%. The R1 side chain, not the beta-lactam ring, is the determinant. Consult a specialist for clinical decisions.
Source: https://pmc.ncbi.nlm.nih.gov/articles/PMC7716594/
Cross-reactivity risk is not definitive; consult an allergy/infectious disease specialist.
Breastfeeding
LactMed
Risk level: Compatible
Low levels in milk; acceptable in nursing mothers, monitor infant for diarrhea, thrush, or rash.
Source: https://www.ncbi.nlm.nih.gov/books/NBK500887/e-lactancia
Risk level: Compatible
Low levels in milk; acceptable in nursing mothers.
Source: https://www.e-lactancia.org/breastfeeding/amoxicillin/product/
Breastfeeding safety requires individual assessment; consult a physician.
Data is in part from e-lactancia.org (CC BY-NC-SA 4.0).