Everything You Need to Know About

Evening primrose (Oenothera biennis)

Botanical family: Onagraceae
Parts used: Seeds
Evening primrose (Oenothera biennis)
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Overview & Health Benefits

From the delicate scent of its bright yellow blooms that open in the evening, the unassuming evening primrose (Oenothera biennis) has a rich history of use in traditional medicine. The blossoms unfurl in the evening, their fragrance filling the air and attracting nocturnal pollinators like moths. This unique flowering pattern also inspired its scientific name, Oenothera, derived from the Greek words "oinos" (wine) and "thera" (to seek or imbibe), hinting at an old belief that the root enhanced the enjoyment of wine (Steckel et al., 2019). While traditionally employed for various ailments, including skin irritations, coughs, and women's health issues (Barnes et al., 2007), evening primrose, and especially the oil extracted from its seeds, continues to be investigated for its potential health benefits, owing largely to its high gamma-linolenic acid (GLA) content (Munir et al., 2017; Timoszuk et al., 2018). Modern research has explored its potential role in inflammatory and hormonal-related conditions.

Key Benefits

  • Skin barrier support
  • Cyclical breast pain relief
  • PMS symptom support
  • Menopausal support
  • Essential fatty acids

Skin Health: Evening primrose oil (EPO) has been studied for atopic eczema. In a systematic review by Sharifi et al. (2024), several trials reported improvements in eczema symptoms, although the authors concluded that the evidence base is heterogeneous and insufficient for firm clinical recommendations. Proposed mechanisms include the role of gamma-linolenic acid (GLA) in supporting essential fatty acid balance relevant to skin barrier function. Studies also suggest that topical application of evening primrose seedcake extract may improve skin hydration and barrier function in small cosmetic-focused studies (Ratz-Łyko et al., 2015). 

Women's Health: Evening primrose has a long history of use in traditional medicine for women's health, notably for cyclic mastalgia (breast pain), a common symptom of premenstrual syndrome (PMS) (Mahboubi, 2019). This effect is hypothesised to relate to its gamma-linolenic acid (GLA) content, which may influence prostaglandin metabolism. While the evidence for EPO's effectiveness in managing other PMS symptoms is less conclusive, research continues in this area (Sharifi et al., 2024). Traditionally, extracts from the leaves and stem bark have also been used for women's reproductive health issues (McIntyre, 2019).

Menopausal Support: Evening primrose oil has been investigated for menopausal vasomotor symptoms, including hot flashes and night sweats. In a single-blind randomized controlled trial (Kazemi et al., 2021), 1,000 mg of EPO taken twice daily for eight weeks did not significantly reduce the frequency or duration of hot flashes compared with placebo; however, the intervention group experienced a statistically significant reduction in the frequency and severity of night sweats. A small randomized clinical trial reported improvements in quality of life and reduction in hot flash intensity (Farzaneh et al., 2013). 

Anti-inflammatory Effects: Evening primrose oil has been studied across a range of inflammatory conditions (Sharifi et al., 2024). In rheumatoid arthritis (RA), some trials of gamma-linolenic acid (GLA) supplementation have reported symptom improvement (Zurier et al., 1996), though outcomes vary depending on study design and dosage. Laboratory research suggests that Oenothera biennis extracts can influence inflammatory signalling pathways, including MAPK and NF-κB, in immune cells (Ma et al., 2020). 

Respiratory Support: Traditionally, evening primrose has been used to ease respiratory problems like coughs, possibly due to its muscle-relaxing (antispasmodic) and soothing (demulcent) properties (Barnes et al., 2007). 

Antioxidant Properties: Evening primrose contains beneficial compounds called phenolic compounds (like gallic acid, caffeic acid, and epicatechin) and flavonoids (like rutin). These act as antioxidants, meaning they help protect the body's cells from damage (Kim & Lee, 2016; Fecker et al., 2020). The amount of these antioxidant compounds extracted from the plant depends on the method used. A method called reflux extraction has been shown to be the most effective way to get the highest concentration of these beneficial antioxidants from evening primrose (Kim & Lee, 2016). This antioxidant activity may contribute to overall health by protecting against oxidative stress, a type of cellular damage linked to various health problems.

Safety Profile

Evening primrose oil (EPO) is generally considered well tolerated when taken as directed (Barnes et al., 2007). Most safety data relate specifically to the oil extracted from the seeds; less is known about other plant parts. Some sources have considered limited use compatible with breastfeeding; however, due to insufficient robust safety data, the European Medicines Agency (EMA) recommends avoiding use during pregnancy and lactation and in children under 12 (EMA, 2011). Mild adverse effects such as headache, nausea, and loose stools have been reported (Barnes et al., 2007; EMA, 2011). Long-term continuous use has not been extensively studied; periodic review of need and response is advisable. Caution is advised if taking anticoagulant or antiplatelet medication or prior to surgery, due to potential effects on bleeding risk (Romm, 2017). EPO may lower the seizure threshold; use with caution in individuals with epilepsy or when taking medicines that reduce seizure threshold, including phenothiazines (Mills & Bone, 2005).

As with any herbal preparation, consultation with a qualified medical herbalist is recommended before use, particularly in the presence of pre-existing conditions or concurrent prescription medications.

References

Barnes, J., Anderson, L.A., & Phillipson, J.D. (2007). Herbal medicines (3rd ed.). Pharmaceutical Press.

Bone, K., & Mills, S. (2013). Principles and practice of phytotherapy (2nd ed.). Elsevier.

European Medicines Agency. (2011). Community herbal monograph on Oenothera biennis L.; Oenothera lamarckiana L., oleum. https://www.ema.europa.eu/en/documents/herbal-monograph/draft-community-herbal-monograph-oenothera-biennis-l-oenothera-lamarckiana-l-oleum-first-version_en.pdf 

Farzaneh, F., Fatehi, S., Sohrabi, M.R., & Alizadeh, K. (2013). The effect of oral evening primrose oil on menopausal hot flashes: A randomized clinical trial. Archives of Gynecology and Obstetrics, 288(5), 1075–1079. https://doi.org/10.1007/s00404-013-2852-6 

Fecker, R., Buda, V., Alexa, E., Avram, S., Pavel, I. Z., Muntean, D., … & Danciu, C. (2020). Phytochemical and biological screening of Oenothera biennis L. hydroalcoholic extract. Biomolecules, 10(6), 818. https://doi.org/10.3390/biom10060818 

Hajiaghayi, M., Dolati-Somarin, A.H., & Gholizadeh, F. (2024). The efficacy of evening primrose in rheumatoid arthritis: A systematic review. Research Journal of Pharmacognosy, 11(2), 71–79. http://doi.org/10.22127/rjp.2023.414090.2212 

Kazemi, F., Masoumi, S.Z., Shayan, A., & Oshvandi, K. (2021). The effect of evening primrose oil capsule on hot flashes and night sweats in postmenopausal women: A single-blind randomized controlled trial. Journal of Menopausal Medicine, 27(1), 8. https://doi.org/10.6118/jmm.20033 

Kim, J. H., & Lee, S.-H. (2016). Antioxidative and antimicrobial activities of Oenothera biennis extracted by different methods. 한국식품저장유통학회지 (Korean Journal of Food Preservation), 23(2),233–238. https://doi.org/10.11002/kjfp.2016.23.2.233 

Ma, R., Chen, Q., Li, H., Wu, S., Lian, M., & Jin, X. (2020). Extract of Oenothera biennis L. stem inhibits LPS-induced inflammation by regulating MAPK and NF-κB signaling pathways. Pakistan Journal of Pharmaceutical Sciences, 33(4),* 1473+.

Mahboubi, M. (2019). Evening primrose (Oenothera biennis) oil in management of female ailments. Journal of Menopausal Medicine, 25(2), 74–82. https://doi.org/10.6118/jmm.18190

McIntyre, A. (2019). The complete herbal tutor. Aeon. 

Mills, S.Y., & Bone, K. (2005). The essential guide to herbal safety. Elsevier Health Sciences.

Moore, M. (1979). Medicinal plants of the mountain West. Museum of New Mexico Press.

Munir, R., Semmar, N., Farman, M., & Ahmad, N.S. (2017). An updated review on pharmacological activities and phytochemical constituents of evening primrose (genus Oenothera). Asian Pacific Journal of Tropical Biomedicine, 7(11), 1046-1054. http://doi.org/10.1016/j.apjtb.2017.10.004 

Ratz-Łyko, A., Arct, J., Pytkowska, K., & Majewski, S. (2015). In vivo and ex vivo evaluation of cosmetic properties of seedcakes. Journal of Cosmetic and Laser Therapy, 17(2), 109–115. https://doi.org/10.3109/14764172.2014.988726

Romm, A. (2017). Botanical medicine for women’s health. Elsevier Health Sciences.

Sharifi, M., Nourani, N., Sanaie, S., & 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, 24(1), 89. https://doi.org/10.1186/s12906-024-04378-5 

Steckel, L.E., Sosnoskie, L.M., & Steckel, S.J. (2019). Common evening-primrose (Oenothera biennis L.). Weed Technology, 33(5), 757-760. https://doi.org/10.1017/wet.2019.53 

Timoszuk, M., Bielawska, K., & Skrzydlewska, E. (2018). Evening primrose (Oenothera biennis) biological activity dependent on chemical composition. Antioxidants, 7(8), 108. https://doi.org/10.3390/antiox7080108 

Zurier, R.B., Rossetti, R.G., Jacobson, E.W., Demarco, D.M., Liu, N.Y., Temming, J. E., … & Laposata, M. (1996). Gamma‐linolenic acid treatment of rheumatoid arthritis. A randomized, placebo‐controlled trial. Arthritis & Rheumatism, 39(11), 1808–1817. https://doi.org/10.1002/art.1780391106