Diphenhydramine and Valbenazine interaction
Diphenhydramine and Valbenazine: the Valbenazine prescribing label describes 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 Valbenazine (INGREZZA) label · effective 2026-04-17
For patients who are CYP2D6 poor metabolizers or are taking a strong CYP2D6 inhibitor, dose reduction may be necessary.
Other important considerations in the differential diagnosis include central anticholinergic toxicity, heat stroke, drug fever, and primary central nervous system pathology.
Use of strong CYP2D6 inhibitors with INGREZZA or INGREZZA SPRINKLE Recommended dosage is 40 mg once daily.
Strong CYP2D6 Inhibitors Clinical Implication: Concomitant use of INGREZZA or INGREZZA SPRINKLE with strong CYP2D6 inhibitors increased the exposure (C max and AUC) to valbenazine’s active metabolite compared with the use of INGREZZA or INGREZZA SPRINKLE alone [see Clinical Pharmacology ( 12.3 , 12.5 )] .
Prevention or Management: Reduce INGREZZA or INGREZZA SPRINKLE dose when INGREZZA or INGREZZA SPRINKLE is coadministered with a strong CYP2D6 inhibitor [see Dosage and Administration ( 2.5 )].
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.