Since Trileptal (oxcarbazepine) is related to carbamazepine (Tegretol, Carbatrol), it causes many of the same side effects. About 25% of people who get a rash from carbamazepine will also get one from Trileptal. On the whole, however, many people find that side effects are less of a problem with Trileptal than with Tegretol. Sometimes their seizures can be controlled better because they can take a higher dose with fewer side effects.

The side effects of Trileptal are usually mild or moderate. The most common side effects are:

• dizziness
• headache
• tiredness
• drowsiness
• double vision
• stomach upset
• loss of coordination

If you notice problems like any of these while you are taking Trileptal, it's probably a good idea to discuss them with your doctor or nurse. You shouldn't stop taking Trileptal or any other seizure medicine without your doctor's advice.

In some patients, especially those taking higher doses of Trileptal, the level of sodium in the blood may become low (hyponatremia). Usually this is not serious, but occasionally it may increase seizure frequency or cause other problems such as tiredness or dizziness. Your doctor may want to check your blood to see if this is happening to you, especially if you are having nausea, a vaguely "unwell" feeling, headache, listlessness, or confusion.

As with many other seizure medicines, you may feel sleepy or less alert when taking Trileptal. Some patients who change from Tegretol to Trileptal report feeling more alert, but it's uncertain how much difference there is between these two medicines in this regard. Until you know how Trileptal affects you, you should be careful about activities that might be dangerous. You should also be very cautious about drinking alcohol, because with Trileptal the neurologic effects of alcohol (such as tiredness, slurred speech, or unsteadiness) may be increased.

Allergic reactions
A small percentage of people taking Trileptal develop a rash within the first few weeks of taking it. If this happens, tell the doctor or nurse right away, to be sure that it's not the beginning of a serious problem. It's rare for the rash to be serious, but don't ignore it. It's often necessary to switch to a different seizure medicine.