Dextromethorphan and quinidine and Voriconazole interaction
Dextromethorphan and quinidine and Voriconazole: 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 Voriconazole label · effective 2026-06-02
…life‑threatening reactions [see Drug Interactions (7) ]: • Eplerenone • Ergot alkaloids (e.g., ergotamine, dihydroergotamine) • Finerenone • Ivabradine • Lurasidone • Naloxegol • Pimozide • Quinidine • Rifabutin [see Clinical Pharmacology (12.3) ] • Sirolimus [see Clinical Pharmacology (12.3) ] • Tolvaptan • Venetoclax: Coadministration at initiation and during the ramp-up…
Pimozide, Quinidine, Ivabradine (CYP3A4 Inhibition) Not Studied In Vivo or In Vitro , but Drug Plasma Exposure Likely to be Increased Contraindicated because of potential for QT prolongation and rare occurrence of torsade de pointes.
From the Dextromethorphan and quinidine (Nuedexta) label · effective 2026-01-22
QT Prolongation: Monitor ECG if concomitant use of drugs that prolong QT interval cannot be avoided or if concomitant CYP3A4 inhibitors used.
This includes patients concomitantly taking/initiating drugs that prolong the QT interval or that are strong or moderate CYP3A4 inhibitors, and patients with left ventricular hypertrophy (LVH) or left ventricular dysfunction (LVD).
Drugs that Prolong QT and Concomitant CYP3A4 Inhibitors Recommend ECG in patients taking drugs with NUEDEXTA that prolong the QT interval and in patients taking concomitant moderate or strong CYP3A4 inhibitors [ see Warnings and Precautions ( 5.3 ) ] .
Strong and moderate CYP3A inhibitors include, but are not limited to, atazanavir, clarithromycin, indinavir, itraconazole, ketoconazole, nefazodone, nelfinavir, ritonavir, saquinavir, telithromycin, amprenavir, aprepitant, diltiazem, erythromycin, fluconazole, fosamprenavir, grapefruit juice, and 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.