Mysoline 250 Tablet is used to control seizures. It contains Primidone which works by decreasing abnormal electrical activity in the brain. In some cases, this medicine may cause side effects such as nausea, headache, vomiting, drowsiness, vertigo, visual impairment, low energy, and impaired coordination. Inform the doctor if you are pregnant or breastfeeding, taking any other medication, or have any pre-existing medical conditions.