Efavirenz and Haloperidol interaction
Efavirenz and Haloperidol: both prescribing labels 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 Efavirenz label · effective 2024-03-31
QT Prolonging Drugs There is limited information available on the potential for a pharmacodynamic interaction between efavirenz and drugs that prolong the QTc interval.
From the Haloperidol (Haloperidol Decanoate) label · effective 2025-02-19
The effect of CYP3A4 inhibition and of decreased CYP2D6 enzyme may be additive.
Drugs that May Decrease Haloperidol Plasma Concentrations Coadministration of haloperidol with potent enzyme inducers of CYP3A4 may gradually decrease the plasma concentrations of haloperidol to such an extent that efficacy may be reduced.
During combination treatment with inducers of CYP3A4, it is recommended that patients be monitored and the haloperidol decanoate dose increased or the dosage interval adjusted, as deemed necessary.
After withdrawal of the CYP3A4 inducer, the concentration of haloperidol may gradually increase and therefore it may be necessary to reduce the dose of haloperidol decanoate, or adjust the dosage interval.
Examples include: CYP3A4 inhibitors – alprazolam; itraconazole, ketoconazole, nefazodone, ritonavir.
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.