Drinking evening primrose or borage oil has no effect on eczema symptoms and the potential harms are not fully understood, concludes a gold-standard review.
Two independent reviewers identified and analysed 27 randomised controlled trials that investigated oral intake of evening primrose oil or borage oil among people with eczema. Nineteen studies assessed evening primrose oil, while eight assessed borage oil; they ranged in duration from three to 24 weeks.
Pooled results for all 19 trials showed there was no significant difference between evening primrose oil and placebo in patient-reported improvement in symptoms, with a non-significant mean difference of -2.2 in favour of placebo on a visual analogue scale (VAS) from 0 to 100. Similarly, physician-reported global improvement in symptoms was no different between evening primrose oil and placebo groups, with a mean difference of -3.6 on a VAS of 0 to 100.
Treatment with borage oil also failed to improve global eczema symptoms compared with placebo, as reported by both patients and doctors, based on a variety of measures of eczema symptom change. No pooled analysis was possible as reported outcomes varied among trials. Both oils, along with placebo, were associated with mild, transient adverse effects, which were mainly gastrointestinal. None of the studies looked at bleeding or thrombotic effects, previously associated with evening primrose oil with long-term use for more than one year.
What this means for GPs
The authors advise that neither evening primrose oil nor borage oil taken orally is an effective eczema treatment and patients should be cautioned about the potential risks of bleeding, inflammation, thrombosis and immunosuppression associated with taking the oils long-term. Lead researcher Dr Joel Bamford, associate professor of family practice at the University of Minnesota, USA, said: ‘Consumers need to be warned that oral evening primrose oil is listed as a known cause of increased bleeding for those taking Coumadin or warfarin, a very common medication.’
Cochrane Library 2013