Key Constituents

Gamma-linolenic acid (GLA) and linoleic acid^{[1, 3, 5, 9, 10, 11]}

Omega-6 essential fatty acids of the seed oil; GLA is the constituent the supplement is taken for.

Gamma-linolenic acid (GLA)

Other seed-oil fatty acids and plant sterols^[10]

Minor lipid constituents.

Phytosterols

Pharmacological Actions

Emollient / skin-soothing^{[1, 5, 10]}

Skin hydration and barrier function in healthy skin

Traditional & Indicated Uses

Eczema^{[2, 11]}Good · 8/10

Eczema / atopic dermatitis - popularly used, but a Cochrane review found oral EPO is NOT effective

more plants for eczema →detailed sources →

Hot flashes^[10]Good · 7/10

Menopausal hot flushes - some trial benefit reported

more plants for hot flashes →detailed sources →

Inflammation (general)

more plants for inflammation (general) →detailed sources →

Menopause

more plants for menopause →detailed sources →

Pain (general)^{[7, 10, 12]}Strong · 9/10

Premenstrual syndrome and cyclical breast pain - some positive but inconsistent trial results (a recent RCT found evening primrose oil reduced cyclical breast-pain severity versus placebo, with a combination of EPO and vitamin E most effective)

more plants for pain (general) →detailed sources →

PMS / premenstrual syndrome^{[10, 12]}Good · 8/10

more plants for pms / premenstrual syndrome →detailed sources →

Skin irritation^[10]Good · 7/10

inferred from emollient action

more plants for skin irritation →detailed sources →

Safety, Cautions & Contraindications

Safety note^{[10, 11]}Info

Evidence is weak and largely negative: a Cochrane review concluded that oral evening primrose oil is not an effective treatment for eczema, and the broader trial literature is heterogeneous. Adverse effects are mild and mainly gastrointestinal.

Safety note^[11]Caution

May increase bleeding risk and has been reported to interact with warfarin; avoid concentrated/medicinal use in pregnancy unless advised by a clinician.

References

REF-1457, REF-1458, REF-1459, REF-1460, REF-1461, REF-1462, REF-1463, REF-1464, REF-1465

References & Sources

Timoszuk, M., Bielawska, K. and Skrzydlewska, E (2018) 'Evening Primrose (Oenothera biennis) Biological Activity Dependent on Chemical Composition', Antioxidants, 7(8), pp. 108. doi:10.3390/antiox7080108 Meta-analysis / review
https://doi.org/10.3390/antiox7080108
Williams, H.C (2003) 'Evening primrose oil for atopic dermatitis', BMJ, 327(7428), pp. 1358-1359. doi:10.1136/bmj.327.7428.1358 Meta-analysis / review
https://doi.org/10.1136/bmj.327.7428.1358
Gad El-Hak, H.N., Kishk, S.M. and Abdelrazek, H.M.A (2024) 'Evening primrose oil enriched with gamma linolenic acid and D/L-alpha tocopherol acetate attenuated carbon tetrachloride-induced hepatic injury model in male rats via TNF-alpha, IL-1beta, and IL-6 pathway', Toxicology Mechanisms and Methods, 34(5), pp. 469-483. doi:10.1080/15376516.2023.2301357 Preclinical
https://doi.org/10.1080/15376516.2023.2301357
Mert, H., Irak, K., Cibuk, S., Yildirim, S. and Mert, N (2022) 'The effect of evening primrose oil (Oenothera biennis) on the level of adiponectin and some biochemical parameters in rats with fructose induced metabolic syndrome', Archives of Physiology and Biochemistry, 128(6), pp. 1539-1547. doi:10.1080/13813455.2020.1781900 Preclinical
https://doi.org/10.1080/13813455.2020.1781900
Farag, M.A., Reda, A., Nabil, M., Elimam, D.M. and Zayed, A (2023) 'Evening primrose oil: a comprehensive review of its bioactives, extraction, analysis, oil quality, therapeutic merits, and safety', Food & Function, 14(18), pp. 8049-8070. doi:10.1039/d3fo01949g Meta-analysis / review
https://doi.org/10.1039/d3fo01949g
Moradi, M., Niazi, A., Heydarian Miri, H. and Lopez, V (2021) 'The effect of evening primrose oil on labor induction and cervical ripening: A systematic review and meta-analysis', Phytotherapy Research, 35(10), pp. 5374-5383. doi:10.1002/ptr.7147 Meta-analysis / review
https://doi.org/10.1002/ptr.7147
Belch, J.J. and Hill, A (2000) 'Evening primrose oil and borage oil in rheumatologic conditions', The American Journal of Clinical Nutrition, 71(1 Suppl), pp. 352S-356S. doi:10.1093/ajcn/71.1.352s Meta-analysis / review
https://doi.org/10.1093/ajcn/71.1.352s
Kalati, M., Kashanian, M., Jahdi, F., Naseri, M. and others (2018) 'Evening primrose oil and labour, is it effective? A randomised clinical trial', Journal of Obstetrics and Gynaecology, 38(4), pp. 488-492. doi:10.1080/01443615.2017.1386165 Randomized trial
https://doi.org/10.1080/01443615.2017.1386165
Ide, T (2023) 'gamma-Linolenic Acid-Rich Oil- and Fish Oil-Induced Alterations of Hepatic Lipogenesis, Fatty Acid Oxidation, and Adipose Tissue mRNA Expression in Obese KK-Ay Mice', Journal of Oleo Science, 72(3), pp. 313-327. doi:10.5650/jos.ess22341 Preclinical
https://doi.org/10.5650/jos.ess22341
Sharifi, M., Nourani, N., Sanaie, S. and Hamedeyazdan, S (2024) 'The effect of Oenothera biennis (Evening primrose) oil on inflammatory diseases: a systematic review of clinical trials', BMC Complementary Medicine and Therapies. doi:10.1186/s12906-024-04378-5 Meta-analysis / review
https://doi.org/10.1186/s12906-024-04378-5
Bamford, J.T.M., Ray, S., Musekiwa, A., van Gool, C., Humphreys, R. and Ernst, E (2013) 'Oral evening primrose oil and borage oil for eczema', Cochrane Database of Systematic Reviews. doi:10.1002/14651858.CD004416.pub2 Meta-analysis / review
https://doi.org/10.1002/14651858.CD004416.pub2
Kumari, J., Amrita, Sinha, A., Kumari, S., Biswas, P. and Poonam (2024) 'Effectiveness of Evening Primrose and Vitamin E for Cyclical Mastalgia: A Prospective Study', Cureus, 16(4). doi:10.7759/cureus.58055 Randomized trial
https://doi.org/10.7759/cureus.58055

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