Hypnotherapy is a healing technique that requires the client to achieve a deep relaxation state, to allow the therapist access into the subconscious mind of the client. The subconscious mind holds the key to all the mysteries that the conscious mind has no clue about, but affects life, in unexplained ways. 
Psychologists like Milton Erickson, who was considered as a pioneer in psychotherapy, has also written accounts of hypnotherapy been used with his clients. A book that opened many closed minds in the west and even the ones with doubt, is “Many lives , Many Masters”, by Dr Brain Weiss, where a well known Psychiatrist chooses to use hypnotherapy with a client suffering from chronic depression, and resulting severe Anxiety , who did not find relief with conventional methods . 
I May have many examples to quote from my personal practice, but I am quoting examples of psychiatrists, because these are people who are trained to only stringent standards of highly controlled double blind studies, one such example is of a popular psychiatrist, who couldn’t yield results of a client with medication and psychotherapy, and hence used Age Regression, to understand the underlying issue that was not being healed by medication, by psychotherapy. In their sessions, the psychiatrist regressed the lady to her teen age years where the issue got triggered, under hypnosis they took a closer look at the situation and was able to analyse, peal into each layer of emotional masks, and was able to get to the core of the issue, resolved it there and hence gained relief at various levels, of her life, allowing her to function normally in her day to day life. 
Hypnosis is a method of sustained, focused concentration. Hypnosis allows the subject to process information in a manner different from the way it is processed in the regular alert state. Because of the power of hypnosis, when integrated into a behaviour modification strategy it can be used in various ways to treat many disorders…… “Psychology Today”
Hypnotherapy has been recognised as a valid medical procedure, in 1958. Since 1995, the National Institutes of Health (NIH) has recommended hypnotherapy as a treatment for chronic pain. The uses and effects of hypnotherapy are numerous, and can allow people live a healthy and happy life
Hypnosis is often confused with losing control, of oneself being out of control this may trigger anxiety in many people, and they might become sceptical of how this therapy could help them. Some people might also imagine being a puppet to the therapist,contrary to popular belief which actually stems from what folks have seen on stage hypnosis. Hypnosis is a natural state that has been studied scientifically and based on many years of clinical research by famous Psychologists such as Sigmund Freud Carl Jung, and more recently, by Dr. Milton Erikson and Dr. John Kappas Simply put, hypnosis is a state of highly focused attention, often associated, and heightened suggestibility.  
 The suggestions given to people under hypnosis appear to be an important part of the mechanism through which the procedure works. While many people won’t accept or respond to an up-front, direct suggestion, under hypnosis, suggestions seem to get into the mind - perhaps through the “back door” of consciousness where they often germinate and take root as important behavioural or psychological changes.
Benefits of hypnotherapy: