What the FDA labels say about taking them together
Lidocaine and phenytoin
Lidocaine's FDA label (Lidocaine Hydrochloride And Dextrose) of February 20, 2026 names phenytoin in its drug interactions section; the phenytoin labels PlainMeds reads (2) do not name lidocaine.
Check it at the source: the lidocaine FDA label on DailyMed (effective May 13, 2024, Fresenius Kabi USA, LLC); the phenytoin FDA label on DailyMed (effective October 15, 2024, Mylan Pharmaceuticals Inc.).
What does the lidocaine label say about phenytoin?
Lidocaine Hydrochloride And Dextrose label (Baxter Healthcare Corporation, February 20, 2026), drug interactionsWhen lidocaine is administered with other antiarrhythmic drugs such as amiodarone, phenytoin, procainamide, propranolol or quinidine, the cardiac effects may be additive or antagonistic and toxic effects may be additive.
Source: FDA drug label (Lidocaine Hydrochloride And Dextrose, NDA018461), Baxter Healthcare Corporation, effective February 20, 2026 (SPL set f21512ea-c7c3-4766-b976-b2c0b5616bf0), via openFDA
Source: FDA drug label (Xylocaine MPF), Fresenius Kabi USA, LLC, effective May 13, 2024 (SPL set d5e0d06f-ba1e-44d4-aa89-39d6c146dc23), via openFDA; the full label on DailyMed
What does the phenytoin label say about lidocaine?
Phenytoin's label (effective October 15, 2024) and its 1 other brand-application label do not name lidocaine 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
| Lidocaine | Phenytoin | |
|---|---|---|
| Labeled for | Pain | Seizures and epilepsy |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.154 per gram 5% ointment | $0.145 per capsule 100 mg capsule |
| Shortage now | In shortage | 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