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Evening primrose oil

Supplement fatty acid women's healthskin & hair
Aka: EPO, Oenothera biennis
Brands seen in Singapore: NOW Foods, Solgar, Sports Research, Nutricost, Vitacost
Third-party tested: Sports Research certifies other products with NSF Certified for Sport, but nothing for evening primrose oil.Certification is granted per product, so check the tub you actually own. Not being listed is not the same as failing.
Not medical advice. Check with your doctor or pharmacist before you start, stop or change the timing of anything you take.
How to use
What it’s for
NCCIH: not enough evidence for any health condition
When to take
Daily
Studied for
The hot-flash trials ran under 6 months
Pros & cons
Pros
  • Generally well tolerated in the trials read
  • No rise in adverse events across 13 mastalgia trials
  • Skin hydration and barrier improved in volunteers
Cons
  • NCCIH: no condition has enough evidence behind it
  • Eczema: not shown to help when taken by mouth
  • Breast pain: no different from placebo in 13 trials
Sources
  1. NCCIH — Evening Primrose Oil: Usefulness and Safety (last updated November 2024), What Have We Learned? · read 2026-08-27
    what it says
    “There's not enough evidence to support the use of evening primrose oil for any health condition.”
  2. NCCIH — Evening Primrose Oil, atopic dermatitis · read 2026-08-27
    what it says
    “Evening primrose oil, taken orally, has not been shown to be helpful for relieving symptoms of atopic dermatitis.”
  3. NCCIH — Evening Primrose Oil, breast pain and other conditions · read 2026-08-27
    what it says
    “Evening primrose oil is probably not more effective than a placebo (an inactive substance) for breast pain … There's insufficient evidence to show whether evening primrose oil is helpful for … rheumatoid arthritis, PMS, and menopause symptoms.”
  4. NCCIH — Evening Primrose Oil, What Do We Know About Safety? · read 2026-08-27
    what it says
    “Evening primrose oil is probably safe for most adults when taken orally … generally well tolerated. The most common side effects are gastrointestinal symptoms such as abdominal pain, nausea, or diarrhea.”
  5. NCCIH — Evening Primrose Oil, pregnancy and breastfeeding · read 2026-08-27
    what it says
    “Evening primrose oil may be safe for use during pregnancy and while breastfeeding, but the evidence is not conclusive … the long-term safety of using evening primrose oil in this way has not been established.”
  6. NCCIH — Evening Primrose Oil, medicines · read 2026-08-27
    what it says
    “If you take any type of medicine, talk with your health care provider before using evening primrose oil or other herbal products; some herbs and medicines interact in harmful ways.”
  7. NCCIH — Evening Primrose Oil, Background (what is in the oil) · read 2026-08-27
    what it says
    “The oil from evening primrose seeds contains omega-6 fatty acids, including gamma-linolenic acid (GLA).”
  8. A Systematic Review and Meta-Analysis of the Efficacy of Evening Primrose Oil for Mastalgia Treatment (Int J Environ Res Public Health 2021) — efficacy · read 2026-08-27
    what it says
    “Thirteen trials with 1752 randomised patients were included. The results showed that EPO has no difference to reduce breast pain compared to topical NSAIDS, danazol, or vitamin E.”
  9. EPO mastalgia meta-analysis, IJERPH 2021 — adverse events · read 2026-08-27
    what it says
    “The EPO does not increase adverse events, such as nausea, abdominal bloating, headache or giddiness, increase weight gain, and altered taste compared to a placebo or other treatments.”
  10. Evening Primrose Oil for Menopause Hot Flashes: Systematic Review and Meta-Analysis (J Menopausal Med 2024) · read 2026-08-27
    what it says
    “The severity of hot flashes was lower when EPO was administered for less than 6 months compared to placebo … The current evidence is insufficient to draw firm conclusions regarding the benefits of EPO in alleviating hot flashes.”
  11. The effect of Oenothera biennis (Evening primrose) oil on inflammatory diseases: a systematic review of clinical trials (BMC Complement Med Ther 2024) — skin outcomes and overall verdict · read 2026-08-27
    what it says
    “Studies in healthy volunteers indicated no significant effect of EPO on epidermal atrophy, nevertheless, positive effects on the skin regarding hydration and barrier function were achieved … contemporary literature is highly heterogeneous”
  12. HSA — Guidelines on Prohibited and Restricted Ingredients in Health Supplements and Traditional Medicines, GL-CHPB-1-012 Rev 001 (Oct 2025), Annex A/B — searched, no row for this ingredient · read 2026-08-27
    what it says
    “The objective of this guideline is to highlight the substances of concern when used in HS and TM and is not meant to be an exhaustive list.”
  13. iHerb Singapore — Women's Health > Evening Primrose Oil category (default order, 1 - 47 of 47 results); first 5 distinct brands: NOW Foods, Solgar, Sports Research, Nutricost, Vitacost · read 2026-08-27
    what it says
    “NOW Foods, Super Primrose, 1,300 mg, 120 Softgels … Solgar, Evening Primrose Oil, 1,300 mg, 60 Softgels … Sports Research, Evening Primrose, 120 Softgels … Nutricost, Evening Primrose Oil, 1,300 mg … Vitacost, Evening Primrose Oil”
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Updated 2026-08-30. Every line above traces to a numbered source. Kozen-X is not a medical device and does not give medical advice. It lists what published sources have written down — nothing more. A pair not listed is unrecorded, not cleared. Before you start, stop or re-time anything, talk to your doctor or pharmacist.