Yes, it’s very effective and perfectly safe to use on children.
Children are often open to suggestion anyway and the use of hypnosis requires very little push as they drop in and out of a hypnotic state naturally throughout the day when they are playing. We often have to be more careful with what we say to children as they can take what is said rather literally.
Hypnosis for children can be really effective and useful especially when it comes to medical procedures. Doctors will put children (and adults for that matter) into a hypnotic state just by walking in to the room so it is vital that they are careful with what they say. I’ve dealt with more than one client who has had a phobia created by the mis-speaking of a medical professional.