Randomised trial, 1990
Does evening primrose oil help PMS symptoms?
No. There were no significant differences between evening primrose oil and placebo. The symptom improvements women experienced were solely due to placebo effect.
What they did
A double-blind, placebo-controlled study of 38 women with moderate PMS. Women received evening primrose oil or placebo for 3 cycles, then switched to the other treatment for 3 more cycles (cross-over design). 10 PMS symptoms plus menstrual symptoms were measured throughout.
What they found
Symptoms improved during the trial, with improvements rapid in the first cycle. However, there were no significant differences in symptom scores between the active evening primrose oil group and the placebo group over 6 cycles. The same improvement pattern occurred regardless of whether women received the active treatment or placebo next.
What it means for you
Evening primrose oil is not more effective than placebo for moderate PMS. Women improved because they were in a study and expected to improve, not because of the oil itself. This was a well-designed study with a reasonable sample of 38 women.
38
women studied
6
total menstrual cycles
10
PMS symptoms measured
About the study
- Original title
- Evening primrose oil and treatment of premenstrual syndrome
- Authors
- Khoo SK, Munro C, Battistutta D
- Journal
- The Medical journal of Australia
- Year
- 1990
- Study design
- Randomised trial
- Participants
- 38
- What was tested
- Evening primrose oil (Efamol and Vita-Glow brands)
- Read the paper
- doi.org/10.5694/j.1326-5377.1990.tb136857.x
Topics
Related studies
Systematic review, 2009
Which herbs, vitamins and minerals help treat PMS?
Systematic review, 2007
What treatments work for premenstrual syndrome?
Study, 2002
Which PMS treatments have good scientific evidence?
Randomised trial, 2000
Which dietary supplements help PMS?
Study, 2024
Does a combination of evening primrose oil, tocotrienol, and vitamin B6 reduce premenstrual symptoms?
Randomised trial, 2024
Does a herbal soft gel capsule with three oils reduce PMS symptoms?