Amoxicillin and Penicillin G interaction
Amoxicillin and Penicillin G: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Amoxicillin label · effective 2026-07-07
AMOXIL is contraindicated in patients who have experienced a serious hypersensitivity reaction (e.g., anaphylaxis or Stevens-Johnson syndrome) to AMOXIL or to other β-lactam antibacterial drugs (e.g., penicillins and cephalosporins).
History of a serious hypersensitivity reaction (e.g., anaphylaxis or Stevens-Johnson syndrome) to Amoxicillin or to other beta-lactams (e.g., penicillins or cephalosporins).
From the Penicillin G (PENICILLIN G POTASSIUM) label · effective 2026-07-24
Other drugs may compete with penicillin G for renal tubular secretion and thus prolong the serum half-life of penicillin.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.