Robin Harford Whilst Oenothera biennis (evening primrose) has a generally favourable safety profile, important cautions exist regarding bleeding risks, drug interactions, contamination, and use during pregnancy.
Primary Safety Concerns
Bleeding Risk: Evening primrose preparations may inhibit platelet aggregation, increasing bleeding risk particularly in individuals with bleeding disorders or those taking anticoagulant or antiplatelet medications. Case reports document newborn bleeding issues following maternal use during pregnancy (Hutcherson et al., 2022).
Pregnancy and Peripartum Use: Not recommended due to insufficient safety data and potential risks to foetus or newborn (Bayles & Usatine, 2009; Hutcherson et al., 2022).
Mild Adverse Effects: Generally mild side effects include gastrointestinal upset, headaches, increased blood pressure, decreased heart rate, pain, nausea, and vomiting. Rare cases of skin bleeding (ecchymoses and petechiae) have been observed (Bayles & Usatine, 2009; Hutcherson et al., 2022).
Drug Interactions: Evening primrose may interact with various medications; consultation with healthcare providers is essential before use (Farag et al., 2023).
Contamination and Quality Issues
Product Purity: Herbal products may be contaminated with heavy metals, pesticides, microbes, or adulterants. Seeds can accumulate copper when grown in contaminated soils, though levels typically remain within food safety standards under normal cultivation (Hutcherson et al., 2022; Dong et al., 2024; Nohutçu et al., 2024).
Lack of Regulation: Evening primrose products are often sold as dietary supplements without strict regulation, increasing contamination risk and dosing inconsistency (Hutcherson et al., 2022).
Toxicity Studies
Animal studies show no significant acute or subacute toxicity at high doses of leaf and sprout extracts, suggesting a favourable safety profile for general consumption (Lakshman et al., 2014; Kim et al., 2021). However, the root contains sterols, triterpenes, tannins, and xanthones whose specific effects and long-term safety in humans remain poorly studied (Timoszuk et al., 2018).
Conclusion
Oenothera biennis is generally safe for most people, but caution is warranted due to bleeding risks, potential drug interactions, and contamination concerns. Individuals with bleeding disorders, those on blood-thinning medications, and pregnant or breastfeeding women should avoid use. Ensure product quality and consult a healthcare provider before consumption, particularly if taking other medications.
References
Bayles, B., & Usatine, R. (2009). Evening primrose oil.. American family physician, 80 12, 1405-8.
Dong, J., Yang, S., Kou, Z., Chen, Y., Yang, T., Gao, P., Zhang, W., Zhang, J., Che, D., & Wang, A. (2024). Oenothera biennis with strong copper toxicity resistance enriches trace copper in seeds under copper pollution soil.. Ecotoxicology and environmental safety, 277, 116382. https://doi.org/10.1016/j.ecoenv.2024.116382
Farag, M., Reda, A., Nabil, M., Elimam, D., & Zayed, A. (2023). Evening primrose oil: a comprehensive review of its bioactives, extraction, analysis, oil quality, therapeutic merits, and safety.. Food & function. https://doi.org/10.1039/d3fo01949g
Hutcherson, T., Cieri‐Hutcherson, N., Lycouras, M., Koehler, D., Mortimer, M., Schaefer, C., Costa, O., Bohlmann, A., & Singhal, M. (2022). Systematic Review of Evening Primrose (Oenothera biennis) Preparations for the Facilitation of Parturition. Pharmacy, 10. https://doi.org/10.3390/pharmacy10060172
Kim, H., Park, S., & Chung, D. (2021). Effect of the Oral Administration of Common Evening Primrose Sprout (Oenothera biennis L.) Extract on Skin Function Improvement in UVB-irradiated Hairless Mice. Pharmaceuticals, 14. https://doi.org/10.3390/ph14030222
Lakshman, S., Jyothi, A., Shasidhar, M., & Kumar, A. (2014). Preliminary phytochemical and toxicity studies of Oenothera biennis. **.
Nohutçu, L., Tunçtürk, M., Tunçtürk, R., & Şelem, E. (2024). Investigation of Nutrient Element Content, Physicochemical and Biochemical Properties of Evening Primrose (Oenothera biennis L.). Osmaniye Korkut Ata Üniversitesi Fen Bilimleri Enstitüsü Dergisi. https://doi.org/10.47495/okufbed.1438434
Timoszuk, M., Bielawska, K., & Skrzydlewska, E. (2018). Evening Primrose (Oenothera biennis) Biological Activity Dependent on Chemical Composition. Antioxidants, 7. https://doi.org/10.3390/antiox7080108