What the FDA labels say about taking them together
Maribavir and phenobarbital
Maribavir's FDA label of January 27, 2026 names phenobarbital in its drug interactions section; the phenobarbital labels PlainMeds reads (2) do not name maribavir. The maribavir label: “With moderate CYP3A4 inducers rifabutin (antimycobacterial) and phenobarbital (anticonvulsant), a dose adjustment is recommended.”
Check it at the source: the maribavir FDA label on DailyMed (effective January 27, 2026, Takeda Pharmaceuticals America, Inc.); the phenobarbital FDA label on DailyMed (effective August 27, 2026).
What does the maribavir label say about phenobarbital?
Maribavir label, drug interactionsWhen coadministered with the moderate CYP3A4 inducers rifabutin (antimycobacterial) or phenobarbital (anticonvulsant), a dose adjustment is recommended.
Maribavir label, warnings and precautionsWith moderate CYP3A4 inducers rifabutin (antimycobacterial) and phenobarbital (anticonvulsant), a dose adjustment is recommended [see Dosage and Administration (2.2 , 2.3) and Drug Interactions (7.3) ].
Source: FDA drug label (Livtencity), Takeda Pharmaceuticals America, Inc., effective January 27, 2026 (SPL set c94fc2c5-e840-4f18-b7d8-d5eacb26d3a0), via openFDA; the full label on DailyMed
What does the phenobarbital label say about maribavir?
Phenobarbital's label (effective August 27, 2026) and its 1 other brand-application label do not name maribavir 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
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
| Maribavir | Phenobarbital | |
|---|---|---|
| Labeled for | n/a | Seizures and epilepsy |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | n/a | $0.213 per tablet 100 mg tablet |
| Shortage now | No current entry | 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