{"entity":{"id":"evening-primrose-oil","kind":"technology","name":"Evening primrose oil","aka":["Oenothera biennis","Gamma-linolenic acid","GLA"],"tldr":"Evening primrose oil is taken for breast pain, hot flushes and skin problems. Evidence is mixed for each, and in cancer the few trials are small: one in liver cancer showed no effect on the tumour or survival. It can increase bleeding with blood thinners, and some products add plant oestrogens, so check the label if your cancer is hormone-sensitive.","summary":"Evening primrose oil is about 10 per cent gamma-linolenic acid. Memorial Sloan Kettering's About Herbs entry reports mixed or limited evidence for eczema, breast pain, premenstrual syndrome and menopausal symptoms: it may reduce hot flush intensity in one study, while other data suggest exercise and lifestyle approaches give better relief. It may reduce skin reactions to azacitidine in myelodysplastic syndrome. Studies in cancer are limited: a trial in liver cancer showed no effect on tumour size or survival, and another suggested gamma-linolenic acid may be an effective adjunct in breast cancer, which has not been confirmed. The oil has no intrinsic oestrogenic activity, but some commercial products combine it with phytoestrogens, so MSK advises caution in hormone-sensitive cancers. It may add to anticoagulant and antiplatelet effects (bleeding time rose significantly in 9 of 12 people taking gamma-linolenic acid for several months), was associated with higher blood pressure in a large population study, and raises levels of antiretroviral drugs. It should not be taken in pregnancy; side effects are mild digestive upset and headache, with one case of lipoid pneumonia after chronic use.","status":"phase-2","asOf":"2026-11-04","links":[{"label":"MSK About Herbs: Evening primrose oil (page last updated 16 February 2022)","url":"https://www.mskcc.org/cancer-care/integrative-medicine/herbs/evening-primrose-oil"}],"tags":["complementary","supportive-care","evidence:insufficient"],"related":["chasteberry","dong-quai"],"cancers":[],"sections":["supportive-care","hormonal"],"technologies":["integrative-oncology","dietary-supplements-treatment-interactions","acupuncture-hot-flushes"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":["b-toxicity-qol"],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"principle":"Gamma-linolenic acid is converted to dihomo-gamma-linolenic acid and anti-inflammatory prostaglandins, and inhibits platelet aggregation.","strengths":["Mild side effects","Small signal for azacitidine skin reactions"],"limitations":["No effect on tumour or survival in a liver cancer trial","Mixed evidence for breast pain and hot flushes","Bleeding interaction; some products contain phytoestrogens"]},"route":"/technologies/evening-primrose-oil/","neighbours":{"technology":[{"id":"acupuncture-hot-flushes","kind":"technology","name":"Acupuncture for hot flushes on endocrine therapy","route":"/technologies/acupuncture-hot-flushes/"},{"id":"chasteberry","kind":"technology","name":"Chasteberry","route":"/technologies/chasteberry/"},{"id":"dietary-supplements-treatment-interactions","kind":"technology","name":"Dietary supplements during cancer treatment: interactions and harms","route":"/technologies/dietary-supplements-treatment-interactions/"},{"id":"dong-quai","kind":"technology","name":"Dong quai","route":"/technologies/dong-quai/"},{"id":"integrative-oncology","kind":"technology","name":"Evidence-based integrative oncology","route":"/technologies/integrative-oncology/"}],"section":[{"id":"hormonal","kind":"section","name":"Hormonal Therapy","route":"/fronts/hormonal/"},{"id":"supportive-care","kind":"section","name":"Supportive Care & Survivorship","route":"/fronts/supportive-care/"}],"bottleneck":[{"id":"b-toxicity-qol","kind":"bottleneck","name":"Toxicity and quality of life are undervalued","route":"/bottlenecks/b-toxicity-qol/"}]}}