Clonic seizure: what to know

Clonic describes repeated muscle contractions and relaxations, often affecting one limb, one side or several muscle groups. Awareness may be preserved or altered, and the person may be confused or tired afterward. A seizure can have many causes, including low blood glucose, alcohol withdrawal, infection or an underlying neurological condition. One seizure does not by itself establish epilepsy; assessment considers the event, medical history and examination.

Stay with the person, move hard or sharp objects away and cushion their head. Loosen tight clothing around the neck, note the start time and observe the movements. Do not restrain them, put anything in their mouth, or give food, drink or medicine until they are fully alert. When the jerking stops, place them on their side if they are breathing and speak calmly while they recover.

Call emergency services if the seizure is prolonged, repeats without recovery, happens in water, causes serious injury, or breathing does not return normally. Get urgent help for a first seizure, pregnancy, diabetes, high fever, severe headache, stiff neck or suspected poisoning. A person who remains unresponsive or has difficulty breathing needs immediate assessment.

Ask what may have triggered the event, whether tests are needed, and how to make a seizure action plan. Record what happened before, during and after it, including sleep loss, medicines, alcohol, illness and recovery.