If a person is having a seizure, make sure there is nothing near them that they can roll onto and hurt themselves, and turn them face up. DO NOT EVER put anything in their mouth (especially your fingers) to "keep them from swallowing their tongue (that's impossible to do). Most seizures go away on their own within 5 minutes. Have someone call 911 or you do it and stay with them until the ambulance arrives. IF the seizure stops but they don't appear to be breathing, you can give them mouth to mouth. Check for a pulse at their neck (carotid artery) and if no pulse start CPR.
Many times, seizure is a complication of an old head injury as well.
Kamalinee Deshpande, M.D.