Cimetidine and Famotidine interaction
Cimetidine and Famotidine: the Famotidine prescribing label 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 Famotidine label · effective 2026-06-06
Famotidine Injection is contraindicated in patients with a history of serious hypersensitivity reactions (e.g., anaphylaxis) to famotidine or other H 2 -receptor antagonists.
History of serious hypersensitivity reactions (e.g., anaphylaxis) to famotidine or other H 2 -receptor antagonists.
Tizanidine (CYP1A2 Substrate) Although not studied clinically, famotidine is considered a weak CYP1A2 inhibitor and may lead to substantial increases in blood concentrations of tizanidine, a CYP1A2 substrate.
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.