Evening primrose oil
A Cochrane review of 27 trials found no difference from placebo for eczema. Trials found no difference for breast pain, premenstrual syndrome or labor timing. Pooled menopause trials found shorter hot flashes, not fewer. A 1-year trial of gamma-linolenic acid found better nerve test results in diabetic neuropathy. Side effects were mild and mostly digestive, similar to placebo.
- Status
- Dietary supplement in the US.
- Also called
- EPO, Oenothera biennis, gamma-linolenic acid, GLA, gamolenic acid, Efamol, Efamast, Epogam, primrose oil
- Taken for
- eczema, breast pain, PMS, hot flashes, menopause, nerve pain in diabetes, cholesterol, skin health, labor preparation
Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on
Shown to help1
What people take it for, and what was found
Shown to help1
Nerve function and pain in diabetic neuropathy
Small trials found better nerve measures over a year with gamma-linolenic acid, and lower pain over 4 weeks with the oil, in diabetic neuropathy.
The numbers and sources
- Effect
- In 111 patients with mild diabetic neuropathy, 480 mg a day of gamma-linolenic acid for a year changed all 16 nerve measures more favorably than placebo, and 13 differences were significant [6]. In 66 patients with painful diabetic neuropathy, 1,000 mg of evening primrose oil twice a day or once a day for 4 weeks lowered pain (visual analog scale) and neuropathy symptom scores against placebo (p<0.001). On the twice-daily dose, pain fell from 5.96 to 4.63 out of 10 [7].
- Population
- Patients at seven centers in the UK and Finland [6]; 66 patients in three groups of 21 to 24 [7].
- Sources
- [6], [7]
- Caveats
- The 1-year trial tested gamma-linolenic acid, the fatty acid in evening primrose oil, not the oil as sold [6]. The pain trial lasted 4 weeks and split its placebo group between once and twice daily dosing [7].
Mixed results1
Hot flashes
Mixed results: one trial found only hot flash severity improved over placebo, and a meta-analysis found only duration fell, in menopausal women.
The numbers and sources
- Effect
- In 56 menopausal women, two 500 mg capsules a day for 6 weeks improved hot flash frequency by 39%, severity by 42% and duration by 19%, against 32%, 32% and 18% on placebo. Only severity differed significantly [4]. A 2025 meta-analysis of 6 RCTs (450 women) found 2.13 fewer hot flashes a day than control and 0.19 lower intensity, neither significant. Hot flash duration fell significantly [5].
- Population
- Women aged 45 to 59 in Iran [4]; menopausal women in 6 RCTs [5].
- Sources
- [4], [5]
- Caveats
- The single trial found only severity differed, while the meta-analysis found only duration differed [4][5]. The meta-analysis graded its evidence moderate to low certainty [5].
Not shown to help4
Eczema
Not shown to improve eczema symptoms more than placebo in children and adults with atopic eczema, across 27 trials.
The numbers and sources
- Effect
- In 27 trials (1,596 participants), evening primrose oil did not improve global eczema symptoms more than placebo, as rated by participants (MD -2.22 on a 0 to 100 scale, 95% CI -10.48 to 6.04, 7 trials) or by doctors (MD -3.26, 95% CI -6.96 to 0.45, 8 trials) [1].
- Population
- Children and adults with atopic eczema [1].
- Sources
- [1]
- Caveats
- Most trials were at low risk of bias. The authors judged the intervals narrow enough to exclude a clinically useful difference [1].
Breast pain
One trial found no difference from control oil in days with breast pain in premenopausal women with severe chronic breast pain.
The numbers and sources
- Effect
- In 120 premenopausal women with severe chronic breast pain, 6 months of evening primrose oil reduced days with pain by 12.3%, against 13.8% on control oil (p 0.73) [2].
- Population
- 120 women in the Netherlands, factorial design with fish oil [2].
- Sources
- [2]
- Caveats
- One trial. All groups improved [2].
Premenstrual syndrome
Limited evidence: the two most tightly controlled of 7 small trials found no benefit for premenstrual syndrome.
The numbers and sources
Cholesterol and triglycerides
Not shown to change total cholesterol, triglycerides, LDL or HDL across 6 trials. Some subgroups saw lower triglycerides or higher HDL.
The numbers and sources
- Effect
- In 6 trials, evening primrose oil did not change total cholesterol, triglycerides, LDL or HDL. In subgroups, triglycerides fell 37.28 mg/dL at 4 g a day or less, and HDL rose 5.47 mg/dL in people with high lipids [8].
- Population
- Adults in randomized trials [8].
- Sources
- [8]
- Caveats
- Subgroup findings from few trials.
Doses studied
The hot flash trial used two 500 mg capsules a day for 6 weeks [4]. The neuropathy trial used 480 mg of gamma-linolenic acid a day for a year [6]. The neuropathy pain trial used 1,000 mg of the oil once or twice a day for 4 weeks [7]. The lipid subgroup effect appeared at 4 g a day or less [8]. The labor trial used 1,000 mg twice a day for 7 days [9].
Risks
Reported risks1
Bleeding with warfarin and long-term use
Case reports: one study suggested more bleeding in people on warfarin, and one report warned of inflammation, thrombosis and immune suppression after a year of use.
The numbers and sources
- Effect
- The Cochrane review cites a study finding that evening primrose oil may increase bleeding in people taking warfarin, and a case report warning of inflammation, thrombosis and immune suppression with use beyond a year [1].
- Population
- Single reports cited in a review [1].
- Sources
- [1]
- Caveats
- The original reports were not reviewed for this page.
Checked, no increase found2
Digestive side effects
Side effects, mainly mild and digestive, were about as common as on placebo in eczema trials.
Seizures
Limited evidence: a 2007 review traced the seizure concern to two early-1980s papers and concluded the link was spurious.
The numbers and sources
- Effect
- A 2007 review traced the concern that evening primrose oil causes seizures to two early-1980s papers. It concluded the association was spurious and called for formularies to remove it [10].
- Population
- Re-examination of the original reports, with animal data [10].
- Sources
- [10]
- Caveats
- A single-author review, not a controlled study.
Claims tested and not found
- That evening primrose oil treats eczema. Global symptoms did not differ from placebo across 27 trials [1].
- That evening primrose oil eases cyclical breast pain. Days with pain fell no more than with control oil [2].
- That evening primrose oil shortens pregnancy or labor. In 80 women at 40 weeks, gestational age at delivery, need for induction and labor duration did not differ from placebo [9].
Sources
- Bamford JT, Ray S, Musekiwa A, et al. Oral evening primrose oil and borage oil for eczema. Cochrane Database of Systematic Reviews. 2013. https://doi.org/10.1002/14651858.CD004416.pub2
- Blommers J, de Lange-de Klerk ES, Kuik DJ, et al. Evening primrose oil and fish oil for severe chronic mastalgia: a randomized, double-blind, controlled trial. American Journal of Obstetrics and Gynecology. 2002. https://doi.org/10.1067/mob.2002.127377a
- Budeiri D, Li Wan Po A, Dornan J. Is evening primrose oil of value in the treatment of premenstrual syndrome? Controlled Clinical Trials. 1996. https://doi.org/10.1016/0197-2456(95)00082-8
- Farzaneh F, Fatehi S, Sohrabi MR, et al. The effect of oral evening primrose oil on menopausal hot flashes: a randomized clinical trial. Archives of Gynecology and Obstetrics. 2013. https://doi.org/10.1007/s00404-013-2852-6
- Larki M, Mohammadi S, Makvandi S. The Effect of Evening Primrose Oil on Menopausal Symptoms Management: A Systematic Review and Meta-Analysis. Journal of Caring Sciences. 2025. https://doi.org/10.34172/jcs.025.33570
- Keen H, Payan J, Allawi J, et al. Treatment of Diabetic Neuropathy With γ-Linolenic Acid. Diabetes Care. 1993. https://doi.org/10.2337/diacare.16.1.8
- Gholami A, Koulaeinejad N, Rahimi M. Effects of evening primrose oil on treating painful diabetic neuropathy: a randomized, double-blind, clinical trial. Journal of Complementary and Integrative Medicine. 2025. https://doi.org/10.1515/jcim-2025-0054
- Khorshidi M, Zarezadeh M, Moradi Moghaddam O, et al. Effect of evening primrose oil supplementation on lipid profile: A systematic review and meta-analysis of randomized clinical trials. Phytotherapy Research. 2020. https://doi.org/10.1002/ptr.6716
- Kalati M, Kashanian M, Jahdi F, et al. Evening primrose oil and labour, is it effective? A randomised clinical trial. Journal of Obstetrics and Gynaecology. 2018. https://doi.org/10.1080/01443615.2017.1386165
- Puri BK. The safety of evening primrose oil in epilepsy. Prostaglandins, Leukotrienes and Essential Fatty Acids. 2007. https://doi.org/10.1016/j.plefa.2007.07.003