Oxcarbazepine Side Effects: What to Expect and When to Call Your Doctor

Oxcarbazepine (Trileptal, Oxtellar XR) is generally well-tolerated, but like all antiepileptic drugs, it comes with a range of possible side effects. Some are mild and often improve as your body adjusts. Others are more serious and require immediate medical attention. This guide helps you know what to expect — and what warning signs to watch for.

Common Side Effects (Usually Manageable)

Most people who take Oxcarbazepine experience at least one of these side effects, especially during the first few weeks or when the dose is increased:

• Dizziness — one of the most frequently reported side effects; often improves over time; be careful when standing up quickly
• Drowsiness/somnolence — taking the medication at bedtime can help minimize daytime drowsiness
• Nausea and vomiting — taking Oxcarbazepine with food (for IR tablets) can reduce stomach upset
• Headache
• Ataxia and coordination problems — feeling unsteady or having difficulty walking; more common at higher doses
• Double vision (diplopia) — visual changes that typically improve as the body adjusts
• Fatigue — feeling more tired than usual, especially early in treatment
• Rash — a mild rash can occur in some patients; any significant rash should be reported to your doctor immediately

Most of these common side effects are most pronounced during dose initiation or escalation and tend to improve over weeks as your body adjusts. If they're severe or persistent, contact your doctor — a dose adjustment may help.

Serious Side Effect: Hyponatremia (Low Sodium) — Know the Signs

One of the most important side effects to know about is hyponatremia (low blood sodium). This occurs in approximately 2–3% of patients taking Oxcarbazepine, and is most likely to develop in the first 3 months of treatment. The risk is higher in elderly patients and those taking diuretics.

Symptoms of hyponatremia include:

• Headache that doesn't respond to usual treatments
• Difficulty concentrating or memory problems
• Confusion or altered mental state
• Weakness, nausea, or vomiting
• Loss of coordination or balance changes
• In severe cases: seizures (can be worsened by low sodium)

Call your doctor right away if you experience any of these symptoms. Your doctor will likely check your blood sodium level periodically — especially in the first few months.

Other Serious Side Effects to Know

• Serious skin reactions (Stevens-Johnson Syndrome/DRESS): Rare but potentially life-threatening. Symptoms include widespread rash, blistering, fever, and swollen lymph nodes. Seek emergency care immediately.
• Suicidal thoughts or behavior: Like all antiepileptic drugs, Oxcarbazepine carries an FDA class warning about increased risk of suicidal ideation. Contact your doctor immediately if you notice worsening depression, hopelessness, or thoughts of self-harm.
• Allergic reactions (anaphylaxis): Swelling of face, lips, throat; difficulty breathing; hives. Call 911 immediately.
• Liver problems: Jaundice, dark urine, abdominal pain. Less common with Oxcarbazepine than with Carbamazepine but still possible.
• Seizure aggravation: Paradoxically, Oxcarbazepine can worsen generalized seizures in some patients. If your seizure frequency increases after starting this medication, contact your doctor.

Special Considerations

• Hormonal contraceptives: Oxcarbazepine can reduce the effectiveness of birth control pills and other hormonal contraceptives. Use a non-hormonal backup method of contraception while taking this medication.
• Driving and operating machinery: Dizziness, drowsiness, and coordination problems can impair driving ability. Do not drive until you know how Oxcarbazepine affects you.
• Alcohol: Alcohol increases the CNS depressant effects of Oxcarbazepine (dizziness, drowsiness). Avoid or limit alcohol while taking this medication.

To learn about medications that interact with Oxcarbazepine and how to manage them, see our guide on Oxcarbazepine drug interactions.