What You Need to Know About Trileptal Side Effects

Trileptal (Oxcarbazepine) is a widely used anticonvulsant prescribed for partial (focal) seizures in adults and children. Like all medications, it comes with potential side effects — some mild, some serious.

Understanding what to expect can help you feel more in control. This guide covers the most common side effects, the serious ones to watch for, and when it's time to call your doctor.

What Is Trileptal?

Trileptal is the brand name for Oxcarbazepine, an antiepileptic drug (AED) that works by blocking voltage-sensitive sodium channels in the brain. This reduces the abnormal electrical activity that causes seizures. It's FDA-approved for partial seizures in adults and children aged 4–16, and is also used off-label for bipolar disorder and nerve pain.

Common Side Effects

Most people who take Trileptal experience mild side effects, especially when first starting or when the dose is increased. These usually improve as your body adjusts over a few weeks.

The most commonly reported side effects include:

• Dizziness — One of the most frequent complaints. It often improves after the first week or two.
• Drowsiness (somnolence) — You may feel sleepy or less alert, especially at higher doses.
• Headache — Usually mild and treatable with over-the-counter pain relievers.
• Nausea and vomiting — Taking Trileptal with food can help reduce stomach upset.
• Double vision (diplopia) — This can happen at higher doses and usually resolves with dose adjustment.
• Fatigue — General tiredness is common, particularly in the first few weeks.
• Balance problems or abnormal gait — Some people feel unsteady on their feet.
• Tremor — Mild shaking, especially in the hands.
• Abdominal pain — Stomach discomfort that usually improves over time.

These side effects are reported in clinical trials at rates between 5% and 30% depending on the dose. Higher doses (above 1,200 mg/day) tend to cause more side effects.

Serious Side Effects

While uncommon, Trileptal can cause serious side effects that require immediate medical attention. Contact your doctor right away — or go to the emergency room — if you experience any of the following:

Hyponatremia (Low Sodium)

This is the most well-known serious side effect of Trileptal. Sodium levels can drop below 125 mmol/L, which can cause:

• Confusion
• Severe headache
• Nausea that won't go away
• Increased seizures
• Difficulty concentrating

Your doctor will monitor your sodium levels with blood tests, especially in the first 3 months. Elderly patients and those taking diuretics are at higher risk.

Serious Skin Reactions

Trileptal has been linked to rare but potentially life-threatening skin conditions:

• Stevens-Johnson syndrome (SJS)
• Toxic epidermal necrolysis (TEN)
• DRESS syndrome (Drug Reaction with Eosinophilia and Systemic Symptoms)

Symptoms include a spreading rash, blistering, fever, and peeling skin. Stop taking Trileptal and seek emergency care immediately if you develop a severe rash. Patients of Asian descent should be screened for the HLA-B*1502 allele before starting, as this genetic marker increases the risk.

Allergic Reactions

Anaphylaxis and angioedema (severe swelling of the face, throat, or tongue) have been reported. Seek emergency help if you have difficulty breathing, swelling, or hives after taking Trileptal.

Suicidal Thoughts

The FDA requires all antiepileptic drugs to carry a warning about an increased risk of suicidal thoughts or behavior. While this risk is small, it's important to watch for changes in mood, behavior, or thoughts of self-harm — especially when starting the medication or changing doses. Contact your doctor immediately if you or a loved one notices these changes.

Blood Disorders

Rarely, Trileptal can cause aplastic anemia, agranulocytosis, or pancytopenia. Signs include unexplained bruising, unusual bleeding, persistent sore throat, or frequent infections.

Side Effects in Specific Populations

Children (Ages 4–16)

Children generally experience the same side effects as adults but may also have more frequent vomiting and upper respiratory infections. Children clear the drug faster than adults, so they may need higher doses per kilogram of body weight.

Elderly Patients

Older adults are at higher risk for hyponatremia and may be more sensitive to dizziness and drowsiness, which can increase fall risk. Doctors typically start at lower doses in this population.

Pregnant Women

Trileptal is Pregnancy Category C. It should only be used during pregnancy if the benefits clearly outweigh the risks. Women taking Trileptal should discuss family planning with their doctor. The medication may also reduce the effectiveness of oral contraceptives.

People With Kidney Problems

If your creatinine clearance is below 30 mL/min, your doctor will likely start you at half the usual dose to avoid side effects from drug buildup.

How to Manage Common Side Effects

Here are some practical tips for dealing with the most frequent Trileptal side effects:

• Dizziness and drowsiness: Avoid driving or operating heavy machinery until you know how Trileptal affects you. Take your dose at bedtime if drowsiness is a problem.
• Nausea: Take Trileptal with food. Eat smaller, more frequent meals.
• Double vision: Report this to your doctor — a dose adjustment usually helps.
• Balance problems: Move slowly when standing up. Use handrails on stairs.
• Fatigue: Give your body time to adjust. Most people feel less tired after 2–4 weeks.

Never change your dose or stop taking Trileptal without talking to your doctor first. Stopping suddenly can cause dangerous breakthrough seizures.

Avoid alcohol while taking Trileptal, as it can make drowsiness and dizziness worse. For a full list of things to watch out for, see our guide to Trileptal drug interactions.

Final Thoughts

Most Trileptal side effects are mild and manageable, especially as your body adjusts to the medication. The key is knowing what to watch for and staying in close contact with your doctor during the first few months of treatment.

If you're just starting to learn about this medication, check out our overview of what Trileptal is and how it's used. And if you're having trouble finding it at your pharmacy, we have a guide on how to find Trileptal in stock near you.