Abstract: A total of 27 studies (1596 participants) met the inclusion criteria: 19 studies assessed evening primrose oil, and 8 studies assessed borage oil. For EPO, a meta-analysis of results from 7 studies showed that EPO failed to significantly increase improvement in global eczema symptoms as reported by participants on a visual analogue scale of 0 to 100 (MD -2.22, 95% CI -10.48 to 6.04, 176 participants, 7 trials) and a visual analogue scale of 0 to 100 for medical doctors (MD -3.26, 95% CI -6.96 to 0.45, 289 participants, 8 trials) compared to the placebo group. Treatment with BO also failed to significantly improve global eczema symptoms compared to placebo treatment as reported by both participants and medical doctors, although we could not conduct a meta-analysis as studies reported results in different ways. With regard to the risk of bias, the majority of studies were of low risk of bias; we judged 67% of the included studies as having low risk of bias for random sequence generation; 44%, for allocation concealment; 59%, for blinding; and 37%, for other biases. Implications for practice Oral borage oil and evening primrose oil lack effect on eczema; improvement was similar to respective placebos used in trials. Oral BO and EPO are not effective treatments for eczema. In these studies, along with the placebos, EPO and BO have the same, fairly common, mild, transient adverse effects, which are mainly gastrointestinal. The short-term studies included here do not examine possible adverse effects of long-term use of EPO or BO. A case report warned that if EPO is taken for a prolonged period of time (more than one year), there is a potential risk of inflammation, thrombosis, and immunosuppression; another study found that EPO may increase bleeding for people on Coumadin® (warfarin) medication. Implications for research Noting that the confidence intervals between active and placebo treatment are narrow, to exclude the possibility of any clinically useful difference, we concluded that further studies on EPO or BO for eczema would be hard to justify. This review does not provide information about long-term use of these products.

Plain-language summary: We included 27 studies, with 1596 adults and children from 12 countries. Of these, 19 studies compared EPO with a placebo (dummy) treatment, and 8 used BO compared with placebo. We looked for evidence of overall improvement in eczema and in quality of life. All 27 studies evaluated overall improvement of eczema, but only 2 studies of EPO measured improvement in quality of life. There was no statistically significant advantage demonstrated for either EPO or BO compared to placebo. In summary, we did not find evidence that eczema improved by taking these products any more than it did by taking placebo. There was some evidence of mild and temporary side-effects for participants with either product or placebo, which were mainly mild, and included temporary headache and upset stomach or diarrhoea. With EPO there is an anticoagulant (blood-thinning) effect when taking these products. There is a warning with the blood thinner warfarin (Coumadin®) that taking EPO can increase bleeding. One report warns that if EPO is taken for a prolonged period of time (more than one year), there is a potential risk of inflammation, thrombosis, and immunosuppression due to slow accumulation of EPO in the tissues. Another reports a single case in which EPO was thought to have produced harms. We found no clinical evidence of such harm in these short-term trials. This systematic review found no evidence that either BO or EPO are effective in treatment of eczema. Both of these products and the placebos used in the studies had similar mild, temporary side-effects, which were mainly gastrointestinal.