Do not put anything in the person’s mouth or between the teeth. People having seizures rarely bite their tongues or cheeks with enough force to cause significant bleeding; however, some blood may be present.

You should not put something in the mouth of someone having a seizure. It used to be thought that people could accidentally choke on their tongue while seizing, so the idea was to hold the tongue down by putting something in their mouth. However, during a seizure people usually clench their jaw, which is one of the strongest muscles in the body. When they clenched their jaw and something was in their mouth, they often broke teeth. So it is no longer recommended to place anything in a seizing person's mouth.