Buspirone and Nefazodone interaction
Buspirone and Nefazodone: both prescribing labels flag 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 Buspirone (Buspirone Hydrochloride) label · effective 2026-03-18
Serotonin Syndrome The development of a potentially life-threatening serotonin syndrome has been reported with SNRIs SSRIs, and other serotonergic drugs, including buspirone, alone but particularly with concomitant use of other serotonergic drugs (including triptans), with drugs that impair metabolism of serotonin (in particular, MAOIs, including reversible MAOIs…
Nefazodone: In a study of steady-state pharmacokinetics in healthy volunteers, coadministration of buspirone (2.5 or 5 mg b.i.d.) with nefazodone (250 mg b.i.d.) resulted in marked increases in plasma buspirone concentrations (increases up to 20-fold in C max and up to 50-fold in AUC) and statistically significant decreases (about 50%) in plasma concentrations…
With 5 mg b.i.d. doses of buspirone, slight increases in AUC were observed for nefazodone (23%) and its metabolites hydroxynefazodone (HO-NEF) (17%) and meta-chlorophenylpiperazine (9%).
Slight increases in C max were observed for nefazodone (8%) and its metabolite HO-NEF (11%).
Other inhibitors and inducers of CYP3A4: Substances that inhibit CYP3A4, such as ketoconazole or ritonavir, may inhibit buspirone metabolism and increase plasma concentrations of buspirone while substances that induce CYP3A4, such as dexamethasone or certain anticonvulsants (phenytoin, phenobarbital, carbamazepine), may increase the rate of buspirone metabolism.
From the Nefazodone (Nefazodone Hydrochloride) label · effective 2025-07-31
Buspirone – In a study of steady-state pharmacokinetics in healthy volunteers, coadministration of buspirone (2.5 or 5 mg BID) with nefazodone (250 mg BID) resulted in marked increases in plasma buspirone concentrations (increases up to 20 fold in C max and up to 50 fold in AUC) and statistically significant decreases (about 50%) in plasma concentrations of the…
With 5 mg BID doses of buspirone, slight increases in AUC were observed for nefazodone (23%) and its metabolites hydroxynefazodone (17%) and mCPP (9%).
If the two drugs are to be used in combination, a low dose of buspirone (e.g., 2.5 mg QD) is recommended.
Subjects receiving nefazodone 250 mg BID and buspirone 5 mg BID experienced lightheadedness, asthenia, dizziness, and somnolence, adverse events also observed with either drug alone.
This is consistent with the interactions observed between nefazodone and triazolam, alprazolam, buspirone, atorvastatin, and simvastatin, drugs metabolized by this isozyme.
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.