This is a controversial subject as hypnotherapy is an unregulated profession at present and each hypnotherapist has their own opinion of the appropriate use of hypnosis.
As a self-regulated profession hypnotherapy takes hold of the more likely contra-indications that can affect sessions including clients that show any form of;
Psychosis | Bi-polar disorder (manic depression) | Suicidal tendencies/ideations
being under the influence of drink or drugs| Epileptics who are not under medication and have had a seizure within the last 12 months
It is not advisable or ethical to induce hypnosis on a client that does not wish to be hypnotised. One should not use hypnosis to achieve goals other than those expressed by the client. Generally, it is difficult to hypnotise a person this way, however, there have been reports of manipulation of ambivalent clients undergoing therapy including hypnotherapy.