Many trials have been conducted and here are two key pieces of research demonstrating the power of hypnotherapy for IBS: Whorwell PJ; Prior A; Faragher EB. Controlled trial of hypnotherapy in the treatment of severe refractory irritable-bowel syndrome.The Lancet 1984, 2: 1232-4.
This study is the earliest and perhaps best study in this research area to date, as it was thoroughly placebo-controlled and showed dramatic contrast in response to hypnosis treatment above the placebo group. Thirty patients with severe symptoms unresponsive to other treatment were randomly chosen to receive 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 wellbeing, but not in their bowel activity pattern. The hypnotherapy patients showed a dramatic improvement in all central symptoms. The hypnotherapy group showed no relapses during the 3-month follow-up period.
Gonsalkorale WM, Houghton LA, Whorwell PJ. Hypnotherapy in irritable bowel syndrome: a large-scale audit of a clinical service with examination of factors influencing responsiveness. Am J Gastroenterol 2002 Apr;97(4):954-61.
This study is notable as the largest case series of IBS patients treated with hypnosis and reported on to date. 250 unselected IBS patients were treated in a clinic in Manchester using 12 sessions of hypnotherapy over a 3-month period, plus home practice between sessions. Marked improvement was seen in all IBS symptoms (overall IBS severity was reduced by more than half on the average after treatment), quality of life, levels of anxiety and depression.
National Institute of Clinical Excellence(NICE)