What the FDA labels say about taking them together
Digoxin and fosphenytoin
Fosphenytoin's FDA label of May 18, 2025 names digoxin in its drug interactions section; the digoxin labels PlainMeds reads (3) do not name fosphenytoin. The fosphenytoin label: “Interacting Agent: Other; Examples: Albendazole, chlorpropamide, clozapine, cyclosporine, digoxin, disopyramide, folic acid, methadone, mexiletine, praziquantel, quetiapine”
Check it at the source: the digoxin FDA label on DailyMed (effective December 5, 2024, Advanz Pharma (US) Corp.); the fosphenytoin FDA label on DailyMed (effective May 18, 2025, Pfizer Laboratories Div Pfizer Inc).
What does the digoxin label say about fosphenytoin?
Digoxin's label (effective December 5, 2024) and its 2 other brand-application labels do not name fosphenytoin in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (LANOXIN), Advanz Pharma (US) Corp., effective December 5, 2024 (SPL set d91e3646-4c63-4512-ab22-db39c085c4dc), via openFDA; the full label on DailyMed
What does the fosphenytoin label say about digoxin?
Fosphenytoin label, drug interactionsInteracting Agent: Other; Examples: Albendazole (decreases active metabolite), chlorpropamide, clozapine, cyclosporine, digoxin, disopyramide, folic acid, methadone, mexiletine, praziquantel, quetiapine
Source: FDA drug label (CEREBYX), NDA020450 (Parke Davis), as published by Pfizer Laboratories Div Pfizer Inc, effective May 18, 2025 (SPL set de5a6711-4abb-4c3d-a18b-266b094ace11), 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
| Digoxin | Fosphenytoin | |
|---|---|---|
| Labeled for | Heart failure, Atrial fibrillation | Seizures and epilepsy |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $0.133 per tablet 125 mcg tablet | n/a |
| Shortage now | No current entry | No current entry |
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