Abnormal results can occur in instances where amateurs, who know the fundamentals of hypnosis, entice friends to become their experimental subjects. Their lack of full understanding can lead to immediate consequences, which can linger for some time after the event. If, for example, the amateur plants the suggestion that the subject is being bitten by mosquitoes, the subject would naturally scratch where the bites were perceived. When awakened from the trance, if the amateur forgets to remove the suggestion, the subject will continue the behavior. Left unchecked, the behavior could land the subject in a physician's office in an attempt to stop the itching and scratching cycle. If the physician is astute enough to question the genesis of the behavior and hypnosis is used to remove the suggestion, the subject may experience long-term negative emotional distress and anger upon understanding exactly what happened. The lack of full understanding, complete training, and supervised experience on the part of the amateur places the subject at risk.
State theorists interpret the effects of hypnotism as due primarily to a specific, abnormal, and uniform psychological or physiological state of some description, often referred to as "hypnotic trance" or an "altered state of consciousness". Nonstate theorists rejected the idea of hypnotic trance and interpret the effects of hypnotism as due to a combination of multiple task-specific factors derived from normal cognitive, behavioural, and social psychology, such as social role-perception and favorable motivation (Sarbin), active imagination and positive cognitive set (Barber), response expectancy (Kirsch), and the active use of task-specific subjective strategies (Spanos). The personality psychologist Robert White is often cited as providing one of the first nonstate definitions of hypnosis in a 1941 article:
As an experienced Hypnotist, I could go on and on about all the different issues that are presented to me by my hypnosis clients. Many times clients have contacted me with problems I have never considered for hypnosis, yet I find that the powerful combination of my extensive hypnotherapy training and experience as a hypnotist provides me with the knowledge and understanding about hypnosis that I need to help them resolve their issues and lead a better and more fullfilling life due to the changes we have been able to achieve during their hypnosis session.
Depending on the purpose of the hypnotherapy (i.e., smoking cessation, weight loss, improvement in public speaking, or addressing some deep emotional turmoil), follow-up may be advisable. When trying to eradicate unwanted habits, it is good practice to revisit the therapist, based upon a date prearranged between the therapist and the patient, to report progress and, if necessary, to obtain secondary hypnotherapy to reinforce progress made.
Since hypnotherapy is an adjunct form of therapy, used along with other forms of psychological or medical treatment, there are many applications. Hypnotherapy can be used to treat anxiety, phobias, substance abuse including tobacco, sexual dysfunction, undesirable spontaneous behaviors, and bad habits. It can be used to help improve sleep, learning disorders, communication, and relationship issues. Hypnotherapy can aid in pain management and help resolve medical conditions such as digestive disorders, skin issues, and gastrointestinal side effects of pregnancy and chemotherapy. It can also be used by dentists to help patients control their fears or to treat teeth grinding and other oral conditions.