As you are blocking a person’s mouth, you need to make sure they can breathe easily through their nose. If a person has a cold, cough, chest infection or are asthmatic it may be wise not to gag them.
Be sure the gag is comfortable to hold in the mouth and don’t leave a person gagged for long. Never leave a gagged person unattended as they can’t regulate how much they drool and there’s a risk of choking.
As the wearer can’t speak, be sure to have a safeword alternative in place such as three quick grunts or dropping something from their hand so they can communicate if they need releasing.