Do not restrain them, and do not put anything in their mouth. Both are instincts and both cause injury. Nobody swallows their tongue; putting an object between the teeth breaks teeth and fingers.
What to do.
- Note the time it started. Everything afterwards depends on it.
- Protect the head — something soft under it — and move furniture and hard objects out of the way.
- Loosen anything tight at the neck.
- Let it run. Most seizures stop on their own within a couple of minutes.
- When the movements stop, turn them onto their side, check breathing, and stay with them. They will be confused, possibly frightened, possibly aggressive from confusion rather than intent. Speak calmly, say who you are and what happened, and give them time.
- Protect their dignity — people are often incontinent during a seizure. Clear onlookers away.
Call the emergency number if: it lasts more than five minutes; a second seizure follows without recovery in between; it is their first ever seizure, as far as anybody knows; they are injured; they do not regain consciousness; it happened in water; they are pregnant; they have diabetes; or you are in any doubt.
Source. World Health Organization, Epilepsy fact sheet, https://www.who.int/news-room/fact-sheets/detail/epilepsy ; European Resuscitation Council, Guidelines 2021, First Aid section, https://cprguidelines.eu/guidelines-2021
What this is not. Reading, not certification.