What the FDA labels say about taking them together
Imipramine and phenytoin
Imipramine's FDA label of August 11, 2026 names phenytoin in its drug interactions section; the phenytoin labels PlainMeds reads (2) do not name imipramine. The imipramine label: “It is desirable to monitor TCA plasma levels whenever a TCA is going to be co-administered with another drug known to be an inhibitor of P450 2D6, The plasma concentration of imipramine may increase when the drug is …”
Check it at the source: the imipramine FDA label on DailyMed (effective August 11, 2026, Leading Pharma, LLC); the phenytoin FDA label on DailyMed (effective October 15, 2024, Mylan Pharmaceuticals Inc.).
What does the imipramine label say about phenytoin?
Imipramine label, drug interactionsIt is desirable to monitor TCA plasma levels whenever a TCA is going to be co-administered with another drug known to be an inhibitor of P450 2D6, The plasma concentration of imipramine may increase when the drug is given concomitantly with hepatic enzyme inhibitors (e.g., cimetidine, fluoxetine) and decrease by concomitant administration with hepatic enzyme inducers (e.g., barbiturates, phenytoin), and adjustment of the dosage of imipramine may therefore be necessary.
Source: FDA drug label (Imipramine Hydrochloride), Leading Pharma, LLC, effective August 11, 2026 (SPL set 490263ce-b4d2-428a-87da-fcd07f85499a), via openFDA; the full label on DailyMed
What does the phenytoin label say about imipramine?
Phenytoin's label (effective October 15, 2024) and its 1 other brand-application label do not name imipramine in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Phenytek), Mylan Pharmaceuticals Inc., effective October 15, 2024 (SPL set 0f94c791-8b07-4b41-927e-c9f28bec5f60), 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
| Imipramine | Phenytoin | |
|---|---|---|
| Labeled for | Depression | Seizures and epilepsy |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $0.0698 per tablet 10 mg tablet | $0.145 per capsule 100 mg capsule |
| 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