Phenobarbital and Verapamil interaction
Phenobarbital and Verapamil: the Verapamil prescribing label describe an interaction that usually calls for monitoring, a dose change, or spacing the doses.
Usually manageable with monitoring or a dose change. Tell your pharmacist you take both.
What the FDA labels say
From the Verapamil (Verapamil Hydrochloride) label · effective 2025-03-25
Phenobarbital Phenobarbital therapy may increase verapamil clearance.
CYP3A4 inducers decrease verapamil levels ( 7.1 )
Inducers of CYP3A4 (e.g., rifampin) have caused a lowering of plasma levels of verapamil.
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.