Sabril can have serious side effects, and so it should only be used after other medicines have been tried, and after careful consideration of possible benefits versus the risks.

The side effect of greatest concern is loss of peripheral vision, so that people may not see well to the sides or high up and low down. According to the manufacturer: Risk increases with total dose and duration of use, but no exposure to Sabril is known that is free of risk of vision loss. Up to 30% of people taking Sabril may have vision loss. Risk of new and worsening vision loss continues as long as Sabril is used, and possibly after discontinuing Sabril. Periodic vision testing (recommended to be every 3 months) is required for patients on Sabril, but cannot reliably prevent vision damage.

Vigabatrin occasionally can produce changes in brain myelin, which is the coating of nerve cells. These changes can be seen with a brain MRI, but their clinical significance is unknown. The most common disease of myelin is multiple sclerosis, but there is no evidence that vigabatrin produces multiple sclerosis. MRI changes usually resolve with discontinuation of vigabatrin.

All seizure medicines, including Sabril, carry warnings about suicidal thinking and tendencies. In a pooled analysis of 11 studies, the FDA noted 4 suicides among 27,863 patients. Epilepsy itself is associated with a higher risk for depression and suicide. You and your family should be alert for the emergence or worsening of the signs and symptoms of depression, any unusual changes in mood or behavior, or the emergence of suicidal thoughts, behavior, or thoughts about self-harm. Behaviors of concern should be reported immediately to your healthcare providers.

Many other side effects were seen, but it is not known whether they were caused by Sabril, other medicines or non-drug reasons.

Laboratory abnormalities: Intermediate

Anemia (low red blood counts) were seen in 6% of patients taking Sabril vs. 2% of those on placebo. Sabril decreases liver enzyme markers AST and ALT. While not a sign of a problem, the decrease could make it harder to detect other problems.

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