|Evening primrose oil doesn't reduce the symptoms of the itchy skin problem eczema, according to a new review of studies.
Herbal supplement makers market primrose oil as helpful in treating eczema, but "I don't think you'll get a specific benefit" from the pills, said Dr. Joel Bamford, the lead author of the review.
Eczema is a common skin disorder, especially among children, marked by itchy, red skin.
Commonly, patients are prescribed steroid medications to treat the problem.
Primrose oil initially showed some promise in studies several decades ago, said Bamford, who is an associate instructor at the University of Minnesota Medical School in Duluth.
But when he tried to replicate the findings, he found that primrose oil didn't seem to work.
Since then, organizations such as the National Institutes of Health and the American Academy of Dermatology have largely brushed aside primrose oil as a treatment for eczema.
But makers of the supplement continue to market the oil as beneficial for eczema. Evening primrose oil sells for about $14 for 100 500-milligram pills.
Dr. Xiu-Min Li, a pediatrics professor at Mount Sinai School of Medicine and the director of the Center for Chinese Herbal Therapy for Allergy and Asthma there, said families are often looking for alternatives to steroids.
The medicines often work well, she said, but when patients stop the treatment, the eczema comes back.
"It makes a family very, very uncomfortable," she said.
To get a better sense of what all the data have to say about the oil, Bamford and his colleagues analyzed the results of 19 studies that compared primrose oil to a fake pill, usually containing vegetable oil or paraffin.
Of seven studies that measured 176 patients' assessments of their symptoms, there were no differences between those who took primrose oil and those who took the placebo.
Similarly, of the eight studies that measured doctors' assessments of 289 patients' symptoms, there were also no differences between the groups of patients, the researchers report in The Cochrane Library.
This isn't to say that people's eczema didn't improve in the studies.
Bamford says about 30 percent of patients might see their eczema clear up for a time, but the same proportion of patients who take a placebo will also see an improvement in their condition.
"Thirty percent will improve because (eczema) comes and goes. It has nothing to do with taking the primrose oil or taking the placebo. It has to do with time," Bamford told Reuters Health.
Li said she believes primrose has some potential to be beneficial, even if that benefit is the same as a placebo.
"If there are some things, even if not as effective as topical steroids, but that can help (patients) at a certain level, I think they have a certain value," she said.
She added that the evidence is not there, however, to recommend that patients take the oil.
Primrose oil is considered safe, and Bamford said the studies did not reveal any side effects.
The oil carries a very slight risk of increased bleeding, but Bamford said it's unlikely.
Bamford said he would not recommend that his patients take it even if it's harmless.
"Do you want to spend your money on something that does not have any known effect?" he said.