Abstract: Four RCTs (307 participants) were included. Two studies compared clinical homeopathy (homeopathic remedy, asafoetida or asafoetida plus nux vomica) to placebo for IBS with constipation (IBS-C). One study compared individualised homeopathic treatment (consultation plus remedy) to usual care for the treatment of IBS in female patients. One study was a three armed RCT comparing individualised homeopathic treatment to supportive listening or usual care. The risk of bias in three studies (the two studies assessing clinical homeopathy and the study comparing individualised homeopathic treatment to usual care) was unclear on most criteria and high for selective reporting in one of the clinical homeopathy studies. The three armed study comparing individualised homeopathic treatment to usual care and supportive listening was at low risk of bias in four of the domains and high risk of bias in two (performance bias and detection bias). A meta-analysis of the studies assessing clinical homeopathy, (171 participants with IBS-C) was conducted. At short-term follow-up of two weeks, global improvement in symptoms was experienced by 73% (46/63) of asafoetida participants compared to 45% (30/66) of placebo participants (RR 1.61, 95% CI 1.18 to 2.18; 2 studies, very low certainty evidence). In the other clinical homeopathy study at two weeks, 68% (13/19) of those in the asafoetida plus nux vomica arm and 52% (12/23) of those in the placebo arm experienced a global improvement in symptoms (RR 1.31, 95% CI 0.80 to 2.15; very low certainty evidence). In the study comparing individualised homeopathic treatment to usual care (N = 20), the mean global improvement score (feeling unwell) at 12 weeks was 1.44 + 4.55 (n = 9) in the individualised homeopathic treatment arm compared to 1.41 + 1.97 (n=11) in the usual care arm (MD 0.03; 95% CI -3.16 to 3.22; very low certainty evidence). In the study comparing individualised homeopathic treatment to usual care, the mean IBS symptom severity score at 6 months was 210.44 + 112.4 (n = 16) in the individualised homeopathic treatment arm compared to 237.3 + 110.22 (n = 60) in the usual care arm (MD -26.86, 95% CI -88.59 to 34.87; low certainty evidence). The mean quality of life score (EQ-5D) at 6 months in homeopathy participants was 69.07 (SD 17.35) compared to 63.41 (SD 23.31) in usual care participants (MD 5.66, 95% CI -4.69 to 16.01; low certainty evidence). For In the study comparing individualised homeopathic treatment to supportive listening, the mean IBS symptom severity score at 6 months was 210.44 + 112.4 (n = 16) in the individualised homeopathic treatment arm compared to 262 + 120.72 (n = 18) in the supportive listening arm (MD -51.56, 95% CI -129.94 to 26.82; very low certainty evidence). The mean quality of life score at 6 months in homeopathy participants was 69.07 (SD 17.35) compared to 63.09 (SD 24.38) in supportive listening participants (MD 5.98, 95% CI -8.13 to 20.09; very low certainty evidence). None of the included studies reported on abdominal pain, stool frequency, stool consistency, or adverse events. The results for the outcomes assessed in this review are uncertain. Thus no firm conclusions regarding the effectiveness and safety of homeopathy for the treatment of IBS can be drawn. Further high quality, adequately powered RCTs are required to assess the efficacy and safety of clinical and individualised homeopathy for IBS compared to placebo or usual care.

Plain-language summary: Four randomised controlled trials (RCTs) with 307 participants with IBS were included. Two RCTs (129 participants) compared a homeopathic remedy (asafoetida and asafoetida plus nux vomica) to a placebo remedy for the treatment of people with IBS-C. One study (23 participants) compared individualised homeopathic treatment to usual care in female patients diagnosed with IBS. One study (94 participants) was a three armed study comparing individualised homeopathic treatment plus usual care, supportive listening plus usual care and usual care. The four trials tested the effects of homeopathic treatment on the severity of IBS symptoms. No conclusions can be drawn from the RCT comparing individualised homeopathic treatment to usual care due to the small number of participants and the low quality of reporting in this trial. This study was carried out in 1990 and usual care for IBS may have changed since then making the results difficult to compare to current treatments. No conclusions can be drawn from the three armed study comparing individualised homeopathic treatment plus usual care, supportive listening plus usual care and usual care due to the small number of participants in the homeopathic treatment arm (n=16). The results of two small studies were combined (129 participants) and this suggested that there may be a possible benefit for clinical homeopathy, using the remedy asafoetida, over placebo for patients with IBS-C at a short-term follow-up of two weeks. However both of the studies were carried out in the 1970s when the reporting of trials was not as comprehensive as it is now and we are very uncertain about these results and cannot suggest a possible benefit for clinical homeopathy. The results for the outcomes assessed in this review are uncertain. Thus no firm conclusions regarding the effectiveness and safety of homeopathy for the treatment of IBS can be drawn. Further high quality RCTs enrolling larger numbers of patients are required to assess the effectiveness and safety of clinical and individualised homeopathy for IBS.