When provided by a licensed and/or board certified hypnotist, hypnosis is safe, absolutely. However, if hypnosis is performed by an amateur on an extremely susceptible mind that suffers from a severe mental illness, the chances of hypnosis being dangerous increase dramatically.
Even though clinical hypnotists are not considered doctors of medicine, we are considered healthcare professionals that are more than qualified to conduct sessions with individuals. Before being hypnotized, make certain that you qualify the clinical hypnotist or hypnotherapist.
I get asked all the time, "What happens if you pass out during one of your comedy hypnosis shows?! Does that mean all of the hypnotized participants will be stuck in a permanent hypnotic state?" It doesn't quite work like that. Although, I do have a safeguard message that I embed in all participants in the event I pass out or suddenly croak on stage. All participants are ready to naturally take themselves out of the hypnotic state should they not hear my voice for a certain amount of time.
It is rare that a subject doesn't emerge from a hypnotic state naturally. However, it does happen that someone remains in a state of confusion if they are still in a semi-hypnotic state. That is why it is very important to only undergo hypnosis under the supervision of a trained professional. As seen in the Facebook video link above, there are certain techniques that a professional hypnotist can perform to help someone that hasn't emerged from a hypnotic state.
The Incredible Hypnotist Helps a Subject Emerge from Hypnosis