Supplement
Evening primrose oil
Fatty acid · Oenothera biennis, Oenothera lamarckiana, Evening Primrose Oil, EPO, gamma-linolenic acid, GLA
Evening primrose oil has been sold for decades against atopic eczema, breast pain, premenstrual complaints and hot flashes. Precisely these uses have been tested in many studies, and there the oil performs no better than placebo: in the Cochrane review on eczema as well as in a meta-analysis on breast pain. The EMA recognizes only a traditional use against itching in dry skin.
What evening primrose oil is
Evening primrose oil is pressed or solvent-extracted from the seeds of the common evening primrose (Oenothera biennis) or of Oenothera lamarckiana. It contains gamma-linolenic acid, GLA for short, an omega-6 fatty acid that is also found in borage oil. It is offered mainly as a dietary supplement in capsules.
In the BK-Score, human evidence stands at 6 out of 10 points. This axis rates the state of knowledge, not the substance: well studied here means that the main promises have been tested and not confirmed. The hype gap stays at 3 out of 10, because advertising targets exactly these uses.
How it is supposed to work
From gamma-linolenic acid the body forms dihomo-gamma-linolenic acid, DGLA for short. This is the basis for the idea of influencing inflammatory skin diseases with the oil. That the fatty acids reach the blood has been measured: healthy women who took fish oil together with evening primrose oil afterwards had more GLA and DGLA in their plasma; arachidonic acid did not fall.
A higher blood level, however, is a surrogate marker, not a clinical outcome. Whether it translates into less itching, less eczema or less breast pain is decided by the controlled studies, and for the advertised uses they are negative.
What is well supported
- A traditional use, officially recognized. The EMA lists evening primrose oil as a traditional herbal medicinal product for the relief of itching in acutely and chronically dry skin. The basis is long-standing use, not proof of efficacy from studies.
- The fatty acids reach the blood. GLA and DGLA rise measurably in plasma after intake.
- Well tolerated. In the meta-analysis on breast pain, nausea, bloating, headache, dizziness, weight gain or changes in taste were no more frequent than with placebo or comparison treatments.
- Well tested, with a clear result. For eczema and breast pain there are so many studies that the question of benefit has been answered, and the answer is no.
What the studies show
Atopic eczema: Cochrane review with 27 trials
Bamford and colleagues analyzed 27 randomized trials with 1,596 participants, 19 of them on evening primrose oil and 8 on borage oil. For overall improvement of eczema, evening primrose oil came to MD −2.22 (−10.48 to 6.04; 7 trials) in the assessment of those affected and MD −3.26 (−6.96 to 0.45; 8 trials) in the assessment of the doctors, on a scale of 0 to 100, both no better than placebo. The risk of bias was low in the majority of trials. The authors write that evening primrose and borage oil have no effect on eczema.
Cyclical breast pain: 13 trials with 1,752 women
Ahmad Adni and colleagues included 13 randomized trials. The number of women with pain relief with evening primrose oil differed neither from placebo nor from vitamin E, danazol or anti-inflammatory pain gels. Side effects were no more frequent.
Premenstrual syndrome: few and small trials
Budeiri and colleagues found only 7 placebo-controlled trials; in 5 the randomization was clearly described. The results could not be pooled cleanly. The two best-controlled trials showed no benefit, but because of their size they could not rule out small effects.
Hot flashes: small trials, inconsistent
A meta-analysis of 6 trials with 450 women found 2.13 fewer hot flashes per day than in the control group, not significant; only the duration of the hot flashes was significantly shorter, and the quality of evidence was moderate to low. In a single 6-week trial with 56 women, only the severity of hot flashes improved significantly more than with placebo, not their frequency or duration.
Where the data stop
- Atopic eczema. The question has been answered: no difference from placebo across many trials with a predominantly low risk of bias.
- Breast pain and PMS. Likewise no benefit over placebo. For cyclical breast pain and PMS, chasteberry is much better studied.
- Menopause. Only small trials with inconsistent results. For hot flashes there are separate pages on hormone therapy and on black cohosh.
- Itching in dry skin. The EMA recognizes this use, but on the basis of tradition. It writes itself that the quality of the studies was very low to moderate and the number of people treated was small.
- Long-term data. The studies ran for weeks to months. Systematic data over years are lacking.
Status, approval and legal
In Germany, evening primrose oil is sold as a dietary supplement and may not be advertised as relieving diseases. In addition, there is a 2018 EU monograph by the EMA that classifies evening primrose oil as a traditional herbal medicinal product against itching in acutely and chronically dry skin. Traditional means: efficacy is plausible but not demonstrated by sufficient studies, and the product has been used safely in this way for at least 30 years, 15 of them in the EU. There is no official maximum amount for dietary supplements.
Safety
The EMA lists as side effects digestive complaints, nausea, soft stools, a rise in temperature, allergic reactions such as skin rash, and headache, each with unknown frequency. In the studies on breast pain, side effects were no more frequent than with placebo. Use is not recommended for children under 12 years or during pregnancy and breastfeeding because of a lack of data. If itching persists for longer than eight weeks, medical advice is indicated.
In the BK-Score, safety stands at 6 out of 10 points; this axis measures how well safety has been studied, not how safe the oil is. This text is information and does not replace medical advice.
BK-Score Well studied – effect not confirmed
| Human evidence | 6 | |
|---|---|---|
| Mechanism | 4 | |
| Safety data | 6 | |
| Hype gap | 3 | |
| Track record of use | 8 |
Evidence 6, because precisely the advertised main uses have been tested in many randomized trials: the Cochrane review with 19 trials on evening primrose oil found no improvement of eczema over placebo (Bamford 2013), a meta-analysis of 13 trials with 1,752 women found none for cyclical breast pain (Ahmad Adni 2021), and in premenstrual syndrome the two best trials showed no benefit (Budeiri 1996); for hot flashes there are only 6 smaller trials with inconsistent results (Larki 2025). Mechanism 4, because the rise of gamma-linolenic acid and dihomo-gamma-linolenic acid in the blood has been measured (Geppert 2008), but the step from there to less inflammation in skin or breast tissue has not been shown in humans. Safety 6, because many trials over weeks to months showed no excess of side effects compared with placebo and an EU monograph exists, but systematic long-term data are lacking and the EMA gives the frequency of side effects as unknown. Hype 3, because the oil has been sold for decades against atopic eczema, breast pain, PMS and menopausal complaints, while the best data there show no difference from placebo. Use 8, because evening primrose oil has been widely used for decades as a medicine and dietary supplement and the EMA recognizes a traditional use against itching in dry skin. Direction negative: the main promises are well studied and not confirmed.
The score rates the state of knowledge, not the substance. “Safety data 9” means well studied – not harmless. “Track record of use 9” means used long and widely – that is not proof of efficacy.
Subjective assessment by Biohacking Kompakt based on published scoring rules – not a scientific rating and not a medical recommendation. Rules and all ratings (German)
Frequently asked questions about evening primrose oil
Does evening primrose oil help with atopic eczema?
According to the Cochrane review, no. In 19 trials of evening primrose oil, eczema overall did not improve more than with placebo, neither in the assessment of those affected nor in that of the doctors. Most trials had a low risk of bias. The authors write that the oil has no effect on eczema.
Does evening primrose oil help against breast pain before the period?
A meta-analysis of 13 trials with 1,752 women found no difference from placebo in the number of women whose pain eased. New or one-sided breast pain should first be clarified by a doctor.
Does evening primrose oil help during menopause?
The data are thin. In a meta-analysis of 6 trials with 450 women, the number of hot flashes did not fall significantly; only their duration was shorter. The quality of evidence was moderate to low.
What is gamma-linolenic acid?
Gamma-linolenic acid is an omega-6 fatty acid found in evening primrose oil and borage oil. The body converts it into dihomo-gamma-linolenic acid, whose level in the blood measurably rises after intake. The studies have not shown that this translates into a benefit in skin diseases.
Is evening primrose oil safe?
In the studies, side effects were no more frequent than with placebo. The EMA lists, among others, digestive complaints, nausea, soft stools, headache and allergic skin reactions; the frequency is unknown. It is not recommended during pregnancy, breastfeeding and in children under 12 years because of a lack of data.
Related
- Similar purposeBlack cohosh (Cimicifuga)
- Same goal: joints & mobilityMSM (methylsulfonylmethane)
- Same goal: joints & mobilityAstaxanthin
- Same goal: joints & mobilityOmega-3 (EPA/DHA)
- Similar purposeChasteberry (Vitex agnus-castus)
- Same goal: joints & mobilityMastic (Mastic Gum)
Sources
- Bamford 2013, Cochrane Database of Systematic Reviews – evening primrose and borage oil for eczema, 27 RCTs (PMID 23633319)
- Ahmad Adni 2021, International Journal of Environmental Research and Public Health – meta-analysis on breast pain, 13 RCTs (PMID 34200727)
- Budeiri 1996, Controlled Clinical Trials – evening primrose oil in premenstrual syndrome (PMID 8721802)
- Larki 2025, Journal of Caring Sciences – meta-analysis on menopausal symptoms, 6 RCTs (PMID 41883983)
- Farzaneh 2013, Archives of Gynecology and Obstetrics – RCT on hot flashes, 56 women (PMID 23625331)
- Geppert 2008, British Journal of Nutrition – fish oil plus evening primrose oil, fatty acids in plasma (PMID 17678567)
- EMA – EU monograph Oenothera biennis L. or Oenothera lamarckiana L., oleum, revision 1 (2018)
- EMA – summary for the public: Evening primrose oil (2018)
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Information only, not medical advice and not a usage or dosage recommendation. Prescription-only and unapproved substances belong in the hands of a physician. Last updated: 2026-10-05.