Sabril (vigabatrin) typically has few unwanted side effects. Because it is usually taken along with another seizure medicine, however, it can be difficult to be sure which effects result from each type of medicine.

In a study of more than 2000 adults, the two most common side effects were:

• drowsiness (reported by 12.5%)
• fatigue (reported by 9%)

Other side effects reported even less often included:

• irritability and nervousness
• dizziness
• headache
• depression
• weight gain

The side effect most often mentioned in children taking Sabril is some form of hyperactivity, which was reported in 11% of 299 children in one study. These children were also taking other seizure medicines at the same time. Problems reported in children less often included sleepiness, insomnia, weight gain, and fatigue.

A few people with epilepsy have more seizures when they take Sabril. This most often happens with people who have myoclonic seizures.

If side effects do not go away within several days or are really bothersome, call the doctor. Sometimes the doctor can help by changing the prescription:

• reducing the overall amount of Sabril
• changing the amount taken at certain times, such as taking a greater proportion of the Sabril at bedtime to reduce daytime sleepiness
• prescribing smaller doses, to be taken more often

No one should stop taking Sabril or change the amount they take or when they take it without their doctor's guidance.

People who have just started taking Sabril (or who have just started taking a larger amount) should be careful during activities that might be dangerous, until they know whether they are having any side effects.

Long-term side effects
As many as 25% of people who take Sabril over a long period develop irreversible damage to the retina that limits their field of vision (the area they can see when looking straight ahead). For this reason, special visual testing at regular intervals is often recommended. Read more in "Visual field defects from Sabril: A study" and "What are the most serious side effects of Sabril?"

Reviewed February 2004 by Steven C. Schachter, MD, epilepsy.com Editorial Board.