It can facilitate the subjective experience of pain. The techniques most commonly used focus on relaxation and imagery, that is a substitute for taking the attention away from pain. Some patients are able to imagine receiving an injection of Morphine feel the instant pain relive. Others can imagine floating in cold or warm water or immersing themselves in a hot bath.
Patients learn how to separate pain from hurt.
Although they may still feel the pain, its perception by mind is of a lesser intensity. They also learn how to transform the feeling of pain with the warmth or tingling. The nice thing about hypnosis is that some can learn how to self hypnotize themselves and feel less pain and discomfort from their illness. People have varying degree of ability to self hypnotize. For some it can be fairly easy.