Guanfacine and Phenobarbital interaction
Guanfacine and Phenobarbital: the Guanfacine 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 Guanfacine (Intuniv) label · effective 2025-06-23
Consider the potential for additive sedative effects with CNS depressant drugs.
…and its plasma concentrations can be significantly affected resulting in an increase in exposure Consider dose reduction [see Dosage and administration (2.7) ] Strong and moderate CYP3A4 inducers, e.g., rifampin, efavirenz Guanfacine is primarily metabolized by CYP3A4 and its plasma concentrations can be significantly affected resulting in a decrease in exposure…
Strong and moderate CYP3A4 inducers decrease guanfacine exposure.
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.