The First Thing You Do Is Nothing Dramatic
Do not grab them. Do not try to stop the shaking. Do not hold their arms down or pin their legs. The convulsion is a wave of electrical misfiring across the brain, the body is going where it is going, and force applied against that movement breaks bones, not seizures. The single first action is to look at the floor around them. If they are near a hard edge, a staircase, a road, or a fire, move the hazard or move them, gently, by sliding, not by restraining. If the ground is clear, leave them where they are and get low beside them.
