Does Gabapentin Interact With Phenytoin?
Phenytoin In a single (400 mg) and multiple dose (400 mg three times a day) study of Gabapentin in epileptic patients (N=8) maintained on phenytoin monotherapy for at least 2 months, gabapentin had no effect on the steady-state trough plasma concentrations of phenytoin and phenytoin had no effect on gabapentin pharmacokinetics.
Severity: Minor
Severity basis: drug interactions section. Combining Gabapentin (Gabapentinoid anticonvulsant) and Phenytoin (Anticonvulsant) is classified as a minor interaction.
What to Do
This is generally a minor interaction, but review it with your pharmacist to be sure it is safe for you.
How This Interaction Works
Interactions like this one can happen when two medicines have overlapping effects, or when one changes how the other is absorbed, broken down, or cleared from the body. Gabapentin is a gabapentinoid anticonvulsant and Phenytoin is a anticonvulsant; together they are documented as a minor interaction. How much this matters depends on your dose, your other medications, and your overall health.
If You Take Both Medications
If you have been prescribed both Gabapentin and Phenytoin, do not start, stop, or change either medication on your own — some medicines are unsafe to stop suddenly. Tell your prescriber and pharmacist that you take both so they can decide whether the combination is right for you, adjust the dose, monitor you more closely, or suggest an alternative.
From the FDA Label
Phenytoin In a single (400 mg) and multiple dose (400 mg three times a day) study of Gabapentin in epileptic patients (N=8) maintained on phenytoin monotherapy for at least 2 months, gabapentin had no effect on the steady-state trough plasma concentrations of phenytoin and phenytoin had no effect on gabapentin pharmacokinetics.
Source: FDA structured product labeling (set_id 01b810b7-f4c8-4412-bbc5-b9220d8770d8).
Check these against your full medication list in our free Interaction Checker
Frequently Asked Questions
Can you take Gabapentin and Phenytoin together?
Gabapentin and Phenytoin have a documented minor interaction. This is generally a minor interaction, but review it with your pharmacist to be sure it is safe for you.
How serious is the Gabapentin and Phenytoin interaction?
It is classified as a minor interaction, based on the FDA label's drug interactions section. A minor interaction is usually limited in effect but is still worth discussing with your care team.
What should I do if I'm taking both Gabapentin and Phenytoin?
If you have been prescribed both Gabapentin and Phenytoin, do not start, stop, or change either medication on your own — some medicines are unsafe to stop suddenly. Tell your prescriber and pharmacist that you take both so they can decide whether the combination is right for you, adjust the dose, monitor you more closely, or suggest an alternative.
This information is educational — not medical advice.
This page is provided for general educational purposes and summarizes publicly available data from sources such as the U.S. Food & Drug Administration. It is not a substitute for the judgment of a licensed clinician and should not be used to start, stop, or change any medication. It may be incomplete or out of date, and individual circumstances vary. Always talk with your prescriber or pharmacist about your specific medications and health conditions. If you think you may have a medical emergency, call 911.
Other Gabapentin Interactions
- Gabapentin + Buprenorphine Naloxone(moderate)
- Gabapentin + Hydrocodone Acetaminophen(moderate)
- Gabapentin + Morphine(moderate)
- Gabapentin + Oxycodone(moderate)
- Gabapentin + Carbamazepine(minor)
- Gabapentin + Codeine(minor)
- Gabapentin + Estradiol(minor)
- Gabapentin + Naproxen(minor)
- Gabapentin + Tramadol(minor)
- Gabapentin + Valproic Acid(minor)
Other Phenytoin Interactions
- Phenytoin + Apixaban(major)
- Phenytoin + Itraconazole(major)
- Phenytoin + Methotrexate(major)
- Phenytoin + Rifampin(major)
- Phenytoin + Rivaroxaban(major)
- Phenytoin + Ticagrelor(major)
- Phenytoin + Amiodarone(moderate)
- Phenytoin + Atorvastatin(moderate)
- Phenytoin + Carbamazepine(moderate)
- Phenytoin + Carbidopa Levodopa(moderate)
- Phenytoin + Cholecalciferol(moderate)
- Phenytoin + Clarithromycin(moderate)
- Phenytoin + Cyclosporine(moderate)
- Phenytoin + Diazepam(moderate)
- Phenytoin + Digoxin(moderate)
- Phenytoin + Doxycycline(moderate)
- Phenytoin + Fluconazole(moderate)
- Phenytoin + Fluoxetine(moderate)
- Phenytoin + Folic Acid(moderate)
- Phenytoin + Furosemide(moderate)
- Phenytoin + Glimepiride(moderate)
- Phenytoin + Hydrocodone Acetaminophen(moderate)
- Phenytoin + Ketoconazole(moderate)
- Phenytoin + Lamotrigine(moderate)
- Phenytoin + Lithium(moderate)
- Phenytoin + Methylphenidate(moderate)
- Phenytoin + Methylprednisolone(moderate)
- Phenytoin + Mirtazapine(moderate)
- Phenytoin + Nifedipine(moderate)
- Phenytoin + Omeprazole(moderate)
- Phenytoin + Oxycodone(moderate)
- Phenytoin + Paroxetine(moderate)
- Phenytoin + Quetiapine(moderate)
- Phenytoin + Sertraline(moderate)
- Phenytoin + Simvastatin(moderate)
- Phenytoin + Tacrolimus(moderate)
- Phenytoin + Topiramate(moderate)
- Phenytoin + Tramadol(moderate)
- Phenytoin + Trazodone(moderate)
- Phenytoin + Sulfamethoxazole Trimethoprim(moderate)
- Phenytoin + Verapamil(moderate)
- Phenytoin + Warfarin(moderate)
- Phenytoin + Alprazolam(minor)
- Phenytoin + Atomoxetine(minor)
- Phenytoin + Azithromycin(minor)
- Phenytoin + Buprenorphine Naloxone(minor)
- Phenytoin + Bupropion(minor)
- Phenytoin + Canagliflozin(minor)
- Phenytoin + Clonazepam(minor)
- Phenytoin + Codeine(minor)
- Phenytoin + Dexamethasone(minor)
- Phenytoin + Glipizide(minor)
- Phenytoin + Levothyroxine(minor)
- Phenytoin + Liothyronine(minor)
- Phenytoin + Metformin(minor)
- Phenytoin + Metronidazole(minor)
- Phenytoin + Modafinil(minor)
- Phenytoin + Ondansetron(minor)
- Phenytoin + Pregabalin(minor)
- Phenytoin + Sucralfate(minor)
- Phenytoin + Tadalafil(minor)
- Phenytoin + Valproic Acid(minor)