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oxcarbazepine vs phenytoin

Side-by-side comparison of oxcarbazepine and phenytoin. Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.

minor Known Drug Interaction

7 DRUG INTERACTIONS • Phenytoin: Increased phenytoin levels. Reduced dose of phenytoin may be required ( 7.1 ) • Carbamazepine, Phenytoin, and Phenobarbital: Decreased plasma levels of MHD (the active metabolite). Dose adjustments may be necessary ( 7.1 ) • Oral Contraceptive: Oxcarbazepine may decrease the effectiveness of hormonal contraceptives ( 7.3 ) 7.1 Effect of Oxcarbazepine on Other Drugs Phenytoin levels have been shown to increase with concomitant use of oxcarbazepine at doses greater than 1200 mg/day [see Clinical Pharmacology ( 12.3 )].

Recommendation: Your doctor may need to lower your dose of phenytoin and will likely check your blood levels more often.

Drug Class
oxcarbazepine Anticonvulsant
phenytoin Anticonvulsant (Hydantoin)
Type
oxcarbazepine Prescription
phenytoin Prescription
Summary
oxcarbazepine

Oxcarbazepine is a medicine used to treat seizures. It helps to control seizures in adults and children.

phenytoin

Phenytoin injection is used to treat certain types of seizures. It can also prevent seizures during or after neurosurgery.

What It Treats
oxcarbazepine

Oxcarbazepine is used to treat partial-onset seizures. These seizures start in one part of the brain. It can be used alone or with other seizure medicines.

phenytoin

This medicine treats generalized tonic-clonic status epilepticus, a type of prolonged seizure. It also helps prevent and treat seizures that may happen during or after brain surgery. Sometimes, it can be used for a short time instead of the oral form of phenytoin when you cannot take the medicine by mouth.

How It Works
oxcarbazepine

Oxcarbazepine works by reducing the electrical activity in the brain. This helps to prevent seizures. It stabilizes overexcited nerve cells.

phenytoin

Phenytoin works by slowing down the signals in the brain that cause seizures. It stabilizes nerve cell membranes, reducing excessive electrical activity. This helps to prevent seizures from starting or spreading.

Common Side Effects
oxcarbazepine
  • Dizziness
  • Sleepiness
  • Double vision
  • Feeling tired
  • Nausea
phenytoin

No common side effects listed.

FAERS Reports
oxcarbazepine
  • Seizure 2,805
  • Tiredness 1,607
  • Feeling dizzy 1,519
  • Convulsion 1,465
  • Headache 1,434
phenytoin
  • The medicine is reacting with another medicine 1,547
  • Seizure 1,382
  • Poisoning from different substances 1,353
  • Convulsion 1,260
  • Prolonged seizure 790
Serious Warnings
oxcarbazepine

This medicine can cause low sodium levels in your blood. Your doctor should check your sodium levels, especially if you take other medicines that can also lower sodium. This medicine may cause suicidal thoughts or actions. Contact your doctor right away if you have any sudden changes in mood, thoughts, or feelings.

phenytoin

This medicine can cause serious heart problems if given too quickly. The injection rate should not be faster than 50 mg per minute for adults, and 1 to 3 mg/kg/min (or 50 mg per minute, whichever is slower) for children. Your heart will be monitored closely during and after the injection.

Pregnancy
oxcarbazepine

Oxcarbazepine may harm your unborn baby. Talk to your doctor if you are pregnant or plan to become pregnant. There is a pregnancy registry for women who take this medicine during pregnancy. You can enroll by calling 1-888-233-2334.

phenytoin

Taking phenytoin during pregnancy may increase the risk of birth defects. If you are pregnant or plan to become pregnant, talk to your doctor about the risks and benefits of this medicine.

Also Compare, Nearby Drugs

How to Read This oxcarbazepine vs phenytoin Comparison

oxcarbazepine is classified in the Anticonvulsant drug class, while phenytoin sits within the Anticonvulsant (Hydantoin) class. Drugs from different classes work through distinct mechanisms, so a head-to-head comparison illustrates trade-offs rather than equivalence. Both drugs are prescription-only, so a licensed provider must authorize use.

Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, oxcarbazepine has 8,830 submissions while phenytoin has 6,332. Those figures reflect cumulative reporting volume, not per-patient risk, so older, widely dispensed drugs typically look worse on count alone. These two drugs have a known minor interaction flagged in FDA labeling, attributed to oxcarbazepine can slow down how your body gets rid of phenytoin, which may cause phenytoin to build up to high levels.. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.

A table cannot substitute for clinical judgment. Effectiveness, tolerability, drug-drug interactions with your other medications, kidney and liver function, pregnancy status, insurance formulary, and price all feed into a decision that only a licensed prescriber can make responsibly. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This page is for educational purposes only, is not medical advice, and should not be used to self-switch between oxcarbazepine and phenytoin - always consult your physician or pharmacist first.

Important: This comparison is for informational purposes only. Drug effects vary between individuals. Always consult your doctor or pharmacist for personalized medical advice.