Cimetidine and Meperidine interaction
Cimetidine and Meperidine: the Meperidine prescribing label flags 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 Meperidine (DEMEROL) label · effective 2026-07-20
Cimetidine Clinical Impact: The concomitant use of cimetidine may reduce the clearance and volume of distribution of meperidine also the formation of the metabolite, normeperidine, in healthy subjects Intervention: If concomitant use cimetidine and DEMEROL Injection is necessary, monitor patients for respiratory depression and sedation at frequent intervals.
Cytochrome P450 3A4 Interaction The concomitant use of DEMEROL Injection with all cytochrome P450 3A4 inhibitors may result in an increase in meperidine plasma concentrations, which could increase or prolong adverse reactions and may cause potentially fatal respiratory depression.
Monitor patients receiving DEMEROL Injection and any CYP3A4 inhibitor or inducer [see Warnings and Precautions (5.5) , Drug Interactions (7) ] .
• Concomitant use with CYP3A4 inhibitors (or discontinuation of CYP3A4 inducers) can result in a fatal overdose of meperidine.
Risks of Concomitant Use or Discontinuation of Cytochrome P450 3A4 Inhibitors and Inducers Concomitant use of DEMEROL Injection with a CYP3A4 inhibitor, such as macrolide antibiotics (e.g., erythromycin), azole-antifungal agents (e.g., ketoconazole), and protease inhibitors (e.g., ritonavir), may increase plasma concentrations of meperidine and prolong opioid…
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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.