A seizure that involves a loss of consciousness and violent muscle contractions.
A grand mal seizure is usually caused by epilepsy, but may have other triggers, such as very low blood sugar, high fever, or a stroke.
The seizure has two stages. Loss of consciousness occurs first and lasts about 10 to 20 seconds, followed by muscle convulsions that usually last for less than two minutes.
Many people will have only one such seizure. Others may need daily anti-seizure medications.