Clonazepam belongs to a class of medications called benzodiazepines. Benzodiazepines are tranquilizers (sedatives) that prevent or stop seizures by slowing down the central nervous system. This makes abnormal electrical activity less likely. As a result, common symptoms include:

• tiredness
• dizziness
• unsteadiness
• impaired attention and memory
• irritability
• hyperactivity (in children)
• drooling (in children)
• depression (usually in adults)
• nausea
• loss of appetite

Scientific studies show that about half of people treated for seizures with clonazepam experience drowsiness and about 30% have problems with coordination. In some cases, these problems diminish with time.

About 25% have behavior problems such as hyperactivity in children. Problems with thinking and behavior are greater with clonazepam than with seizure medicines like Tegretol, Dilantin, and Depakote.

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

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

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

People who have just started taking clonazepam (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.

Reviewed March 2005 by Steven C. Schachter, MD, epilepsy.com Editorial Board.