Lancet. 1984 Dec 1;2(8414):1232-4.
Controlled trial of hypnotherapy in the treatment of severe refractory irritable-bowel syndrome.
This was the earliest formal study of hypnosis treatment for IBS and remains to date one of the best studies in this research area, as it was thoroughly placebo-controlled and showed dramatically greater improvement from hypnosis treatment above the placebo. Thirty patients with severe symptoms that had been unresponsive to other treatment were randomly chosen to receive either 7 sessions of hypnotherapy (15 patients) or 7 sessions of psychotherapy plus placebo pills (15 patients). The psychotherapy group showed a small but significant improvement in abdominal pain and distension, and in general well-being but not bowel activity pattern. The hypnotherapy patients showed a dramatic improvement in all IBS symptoms. The hypnotherapy group showed no relapses during the 3-month follow-up period.
Figure adapted from the above paper by Whorwell and colleagues, showing the changes in the hypnosis group and the comparison treatment group in well-being (upper left-hand graph) and IBS symptoms during the 2-week baseline and 12-week treatment period
30 patients with severe refractory irritable-bowel syndrome were randomly allocated to treatment with either hypnotherapy or psychotherapy and placebo. The psychotherapy patients showed a small but significant improvement in abdominal pain, abdominal distension, and general well-being but not in bowel habit. The hypnotherapy patients showed a dramatic improvement in all features, the difference between the two groups being highly significant. In the hypnotherapy group no relapses were recorded during the 3-month follow-up period, and no substitution symptoms were observed.
Link to full paper with PMID: 6150275