Background: Acne is a chronic skin disease characterised by inflamed spots and blackheads on the face, neck, back, and chest. Cysts and scarring can also occur, especially in more severe disease. People with acne often turn to complementary and alternative medicine (CAM), such as herbal medicine, acupuncture, and dietary modifications, because of their concerns about the adverse effects of conventional medicines. However, evidence for CAM therapies has not been systematically assessed.
Objectives: To assess the effects and safety of any complementary therapies in people with acne vulgaris.
Search methods: We searched the following databases from inception up to 22 January 2014: the Cochrane Skin Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL; 2014,Issue 1), MEDLINE (from 1946), Embase (from 1974), PsycINFO (from 1806), AMED (from 1985), CINAHL (from 1981), Scopus (from 1966), and a number of other databases listed in the Methods section of the review. The Cochrane CAM Field Specialised Register was searched up to May 2014. We also searched five trials registers and checked the reference lists of articles for further references to relevant trials.
Selection criteria: We included parallel-group randomised controlled trials (or the first phase data of randomised cross-over trials) of any kind of CAM, compared with no treatment, placebo, or other active therapies, in people with a diagnosis of acne vulgaris.
Data collection and analysis: Three authors collected data from each included trial and evaluated the methodological quality independently. They resolved disagreements by discussion and, as needed, arbitration by another author.
Main results: We included 35 studies, with a total of 3227 participants. We evaluated the majority as having unclear risk of selection, attrition, reporting, detection, and other biases. Because of the clinical heterogeneity between trials and the incomplete data reporting, we could only include four trials in two meta-analyses, with two trials in each meta-analysis. The categories of CAM included herbal medicine, acupuncture, cupping therapy, diet, purified bee venom (PBV), and tea tree oil. A pharmaceutical company funded one trial; the other trials did not report their funding sources.Our main primary outcome was 'Improvement of clinical signs assessed through skin lesion counts', which we have reported as 'Change in inflammatory and non-inflammatory lesion counts', 'Change of total skin lesion counts', 'Skin lesion scores', and 'Change of acne severity score'. For 'Change in inflammatory and non-inflammatory lesion counts', we combined 2 studies that compared a low- with a high-glycaemic-load diet (LGLD, HGLD) at 12 weeks and found no clear evidence of a difference between the groups in change in non-inflammatory lesion counts (mean difference (MD) -3.89, 95% confidence interval (CI) -10.07 to 2.29, P = 0.10, 75 participants, 2 trials, low quality of evidence). However, although data from 1 of these 2 trials showed benefit of LGLD for reducing inflammatory lesions (MD -7.60, 95% CI -13.52 to -1.68, 43 participants, 1 trial) and total skin lesion counts (MD -8.10, 95% CI -14.89 to -1.31, 43 participants, 1 trial) for people with acne vulgaris, data regarding inflammatory and total lesion counts from the other study were incomplete and unusable in synthesis.Data from a single trial showed potential benefit of tea tree oil compared with placebo in improving total skin lesion counts (MD -7.53, 95% CI -10.40 to -4.66, 60 participants, 1 trial, low quality of evidence) and acne severity scores (MD -5.75, 95% CI -9.51 to -1.99, 60 participants, 1 trial). Another trial showed pollen bee venom to be better than control in reducing numbers of skin lesions (MD -1.17, 95% CI -2.06 to -0.28, 12 participants, 1 trial).Results from the other 31 trials showed inconsistent effects in terms of whether acupuncture, herbal medicine, or wet-cupping therapy were superior to controls in increasing remission or reducing skin lesions.Twenty-six of the 35 included studies reported adverse effects; they did not report any severe adverse events, but specific included trials reported mild adverse effects from herbal medicines, wet-cupping therapy, and tea tree oil gel.Thirty trials measured two of our secondary outcomes, which we combined and expressed as 'Number of participants with remission'. We were able to combine 2 studies (low quality of evidence), which compared Ziyin Qinggan Xiaocuo Granule and the antibiotic, minocycline (100 mg daily) (worst case = risk ratio (RR) 0.49, 95% CI 0.09 to 2.53, 2 trials, 206 participants at 4 weeks; best case = RR 2.82, 95% CI 0.82 to 9.06, 2 trials, 206 participants at 4 weeks), but there was no clear evidence of a difference between the groups.None of the included studies assessed 'Psychosocial function'.Two studies assessed 'Quality of life', and significant differences in favour of the complementary therapy were found in both of them on 'feelings of self-worth' (MD 1.51, 95% CI 0.88 to 2.14, P < 0.00001, 1 trial, 70 participants; MD 1.26, 95% CI 0.20 to 2.32, 1 trial, 46 participants) and emotional functionality (MD 2.20, 95% CI 1.75 to 2.65, P < 0.00001, 1 trial, 70 participants; MD 0.93, 95% CI 0.17 to 1.69, 1 trial, 46 participants).Because of limitations and concerns about the quality of the included studies, we could not draw a robust conclusion for consistency, size, and direction of outcome effects in this review.
Authors' conclusions: There is some low-quality evidence from single trials that LGLD, tea tree oil, and bee venom may reduce total skin lesions in acne vulgaris, but there is a lack of evidence from the current review to support the use of other CAMs, such as herbal medicine, acupuncture, or wet-cupping therapy, for the treatment of this condition. There is a potential for adverse effects from herbal medicines; however, future studies need to assess the safety of all of these CAM therapies. Methodological and reporting quality limitations in the included studies weakened any evidence. Future studies should be designed to ensure low risk of bias and meet current reporting standards for clinical trials.