What the FDA labels say about taking them together
Phenobarbital and voriconazole
Voriconazole's FDA label of February 26, 2026 names phenobarbital in its drug interactions section; the phenobarbital labels PlainMeds reads (2) do not name voriconazole. The voriconazole label: “Contraindicated”
Check it at the source: the phenobarbital FDA label on DailyMed (effective August 27, 2026); the voriconazole FDA label on DailyMed (effective February 26, 2026, Roerig).
What does the phenobarbital label say about voriconazole?
Phenobarbital's label (effective August 27, 2026) and its 1 other brand-application label do not name voriconazole in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Phenobarbital), Chartwell RX, LLC, effective August 27, 2026 (SPL set 74428144-fb24-40a5-a670-3b876e2d116c), via openFDA; the full label on DailyMed
What does the voriconazole label say about phenobarbital?
Voriconazole label, drug interactionsDrug/Drug Class (Mechanism of Interaction by the Drug): Long Acting Barbiturates (e.g., phenobarbital, mephobarbital) (CYP450 Induction); Voriconazole Plasma Exposure (C max and AUC τ after 200 mg every 12 hours): Not Studied In Vivo or In Vitro, but Likely to Result in Significant Reduction; Prevention or Management Recommendations: Contraindicated
Source: FDA drug label (Voriconazole, NDA208562), Xellia Pharmaceuticals USA LLC, effective January 11, 2023 (SPL set 9ec6eda2-2f15-423b-9ec6-819379a426e1), via openFDA
Source: FDA drug label (VFEND), NDA021630 (Pf Prism Cv), as published by Roerig, effective February 26, 2026 (SPL set ce3ef5cf-3087-4d92-9d94-9eb8287228db), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Phenobarbital | Voriconazole | |
|---|---|---|
| Labeled for | Seizures and epilepsy | Fungal infections |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.213 per tablet 100 mg tablet | $1.88 per tablet 200 mg tablet |
| Shortage now | A presentation being discontinued | A presentation being discontinued |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once