When it comes to defining what hypnosis can and cannot do, I can only share with you what I know as fact, first hand, based on my own experience. In my opinion, if hypnosis has any limitations, they will be a direct result of unrealistic expectations.  

I have seen hypnosis work in conjunction with traditional medicine. I have seen significantly reduced impact of side effects to certain treatments like chemotherapy. I have seen a reduction in pain, and increased tolerance to chemo and other treatments. I have witnessed a greatly improved ability to cope with the emotional strain of terminal illness with the help of hypnosis. But I have never seen hypnosis cure cancer. And I wouldn't state that it can. Maybe others have made such claims, and if in fact they have achieved such heights of success with hypnosis, they can and should attest to it. But ethically, I cannot speak to speculation or risk imposing any false hopes upon my clients.

Other questionable benefits of hypnosis include actual physical changes in the body like enlarged breasts, or increased height. Perhaps if I were to follow the pursuit of one such benefit for an extended period of time, by specializing in breast enlargement for instance, I might be able to report back to you that it does in fact work, and that I did achieve the desired result. But again, I can only attest to what I know with certainty.  

In my personal and professional opinion, an ethical hypnotherapist will promise only what he knows he can deliver. There are enormous benefits from listening to self hypnosis CDs and downloads. Yet there is no need to resort to falsifying facts. I've seen therapists selling hypnosis products for a wide range of issues. An unfortunate risk in making unrealistic promises is that people will lose faith in hypnosis altogether and deny themselves the benefits of this incredible tool because of the poor ethics of one or a few persons.

I certainly want people to try self hypnosis, and I wholehearted believe that everyone can benefit from it to some degree, but I also care to be able to live with myself, and respect the face in the mirror, and I would not go to unlimited lengths to get people to try it or purchase my product.  

Those who have tried self hypnosis will need no further convincing, and those who haven't should not have to fear false promises.