People who have had a condition called porphyria should not take Mysoline (primidone). Those who are sensitive to phenobarbital also are advised to avoid it, because the body produces phenobarbital when it processes Mysoline.

Women who are pregnant or may become pregnant, and those who are breastfeeding should be cautious about using Mysoline. The manufacturer suggests that breastfeeding be discontinued if the baby is unusually sleepy. Other seizure medicines may be a better choice for pregnant women and nursing mothers.

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