- Evening primrose oil
- Night willow herb
- Fever plant
- King's cure-all
For Patients & Caregivers
How It Works
Evidence for whether evening primrose oil can relieve pain or skin conditions is mixed, and it has not been adequately studied for its effects on cancer.
Evening primrose oil has been used for a variety of conditions including rheumatoid arthritis, premenstrual syndrome, menopause symptoms, and eczema. It has also been used for several types of pain, including breast and diabetic nerve pain.
Studies in humans are limited and mixed on whether it can help relieve breast pain, PMS, nerve pain, or skin inflammation. Other data suggest benefits in conditions such as rheumatoid arthritis and multiple sclerosis, but more studies are needed to confirm these effects. Interestingly, although evening primrose oil may decrease hot flash intensity in menopausal women, other data suggest that behavioral or lifestyle changes such as increased exercise provide better relief.
Very few studies have been conducted in cancer patients. Although evening primrose oil does not have hormonal properties, some products that contain it may also contain phytoestrogens, which are plant-derived sources of estrogen. Therefore, patients with hormone-sensitive cancers should use evening primrose oil products with caution.
To treat cancer
Evening primrose oil has not been studied adequately for cancer. In an older study, it had no effect on tumor size or survival in patients with liver cancer. In a small study of breast cancer patients, those who received a compound derived from evening primrose oil in addition to tamoxifen had enhanced response to treatment.
To treat diabetic neuropathy
Results from older studies to improve symptoms of diabetic nerve pain were mixed.
To treat eczema
Clinical trials show conflicting results, but some trials show benefit in skin conditions caused by specific drugs to treat acne and myelodysplastic syndrome. However, other large analyses have concluded both evening primrose oil and borage oil are not effective for eczema.
To treat GI disorders such as colitis or irritable bowel syndrome
One clinical trial studied the effects of evening primrose oil on ulcerative colitis, showing weak effects. In general, there is little support for this use.
To relieve breast pain
A handful of clinical trials support this use, especially for breast pain associated with the menstrual cycle.
To relieve menopausal symptoms
One study found that evening primrose oil was no better than placebo at relieving hot flashes. Another suggests it may improve quality of life and decrease hot flash intensity. Other data suggest that behavioral or lifestyle changes such as increased exercise provide better relief.
To prevent premenstrual syndrome
Results of clinical trials are inconsistent.
To reduce inflammation of rheumatoid arthritis
Clinical studies suggest that evening primrose oil may be useful for reducing symptoms.
Do Not Take If
- You are pregnant: Side effects have included delivery complications, as well as skin conditions and bruising in a newborn.
- You are taking anticoagulants or antiplatelet agents: Evening primrose oil may increase bleeding risk or the effects of these drugs.
- You are taking blood pressure medications: Even though no interactions have been reported, a large population-based study showed that evening primrose oil can increase blood pressure.
- You are taking antiretrovirals: When used concurrently, evening primrose oil significantly increases the levels of antiretroviral drugs, and may increase the risk of adverse effects.
- Minor: Abdominal pain, indigestion, nausea, softening of stools, headaches
- Labor abnormalities: Serious labor problems occurred among women who used evening primrose oil to shorten gestation and labor times.
Red dots and large bruises on a newborn: The mother used raspberry leaf tea and evening primrose oil 1 week before childbirth.
Pneumonia: In a 50-year-old woman following chronic use of evening primrose oil, caused by breathing in fat particles from this supplement into the lungs.
For Healthcare Professionals
Derived from the plant Oenothera biennis, evening primrose oil is used for rheumatoid arthritis, premenstrual syndrome, eczema, fatigue, diabetic neuropathy, and mastalgia. The mucilaginous stem and leaf juices have been used as a poultice to treat minor bruises and wounds, and soothe skin inflammation (25). Evening primrose oil is thought to improve skin moisture and reduce transepidermal water loss (26). It is also among the popular natural products used to relieve menopausal symptoms (27) (28). In vitro, evening primrose oil demonstrates anti-inflammatory activity (29) and inhibits platelet aggregation (6) (7). In animal models, it exerts anti-angiogenic, anti-inflammatory, and anti-arthritic effects (30), and improved cardiac recovery after myocardial infarction (31).
Human studies on whether evening primrose oil is helpful for skin conditions are limited and mixed. Small trials suggest benefit in atopic dermatitis (18) (25) (32), but other analyses did not find evening primrose oil or borage oil effective for eczema (23) (33). In acne patients treated with oral isotretinoin, evening primrose oil may improve xerotic cheilitis (34). It may also reduce 5-azacitidine-induced skin reactions in patients with myelodysplastic syndrome (19). Other preliminary data suggest benefit in some lipid profiles (53), rheumatoid arthritis symptoms (21), ulcerative colitis (35) (36), or for ocular surface diseases such as dry eye (37) (38), but early studies in diabetic neuropathy were equivocal (39). In multiple sclerosis patients, it may improve fatigue and quality of life (54), and along with hemp seed and a diet high in antioxidants, it may improve clinical and immunological parameters (40) (41) (42).
Additional data indicate that supplementation with vitamin E and evening primrose oil reduced cyclical mastalgia (20), but other analyses did not find improvements in breast pain (1) (43) or premenstrual syndrome (22). Evening primrose oil may improve quality of life and decrease hot flash intensity in menopausal women (44), although other data suggest that behavioral/lifestyle approaches such as exercise provide better relief (28). In postmenopausal women, it improved related psychological symptoms (55), but more study is needed to confirm these effects.
Studies in cancer patients are quite limited, with one trial involving liver cancer patients that showed no effect on tumor size or survival (45), and another that suggested gamma-linolenic acid may be an effective adjunctive therapy for breast cancer (4). Although evening primrose oil does not have intrinsic estrogenic properties, some commercial products combine evening primrose oil with phytoestrogens. Therefore, patients with hormone-sensitive cancers should use evening primrose oil products with caution.
Mechanism of Action
Evening primrose oil is rich in omega-6 gamma-linolenic acid (GLA), which can be converted directly to the prostaglandin precursor dihomo-GLA (DGLA) (2) (3). Administration of the oil may benefit individuals unable to metabolize cis-linolenic acid to GLA, producing subsequent intermediates of metabolic significance including prostaglandins (2) (3).
In vitro, long-chain fatty alcohols such as hexacosanol, tetracosanol, docosanol, and octocosanol demontrate anti-inflammatory activity (29). In animal models, benefits on cardiac recovery after myocardial infarction are attributed to its hypocholesterolemic effect and indirect influence on prostaglandins and cytokine synthesis (31). In arthiritis models, evening primrose oil normalized body weight, angiopoietin-1, and tumor necrosis factor-alpha levels, and reduced malondialdehyde levels, synovial hyperplasia, and inflammatory cell invasion in joint tissues (30).
In patients with multiple sclerosis, evening primrose oil accelerates anti-inflammatory responses and prevents pro-inflammatory cytokine production while helping to maintain fatty acid membranes and optimizing balance between saturated and unsaturated fatty acids (40). Increases in plasma GLA and its metabolite DGLA seen with evening primrose oil supplementation has correlated with clinical improvements in atopic dermatitis (32) and produced dose-dependent effects on serum fatty acid levels and eczema severity scores (25). Inhibition of cheilitis is attributed to GLA’s effects on stratum corneum maturation, differentiation, and preservation of its permeability barrier (34). Antiplatelet and anticoagulant effects are likely related to decreased thromboxane B2 synthesis induced by evening primrose oil (46) (47).
- Pregnant women should not take evening primrose oil due to increased risk of pregnancy complications (8) (48).
- Patients with hormone-sensitive cancers should use evening primrose oil products with caution, because even though it does not possess estrogenic properties on its own, some commercial evening primrose oil products may contain other phytoestrogen ingredients.
Minor: abdominal pain, indigestion, nausea, softening of stools, and headaches (25).
Labor abnormalities: When used to shorten gestation and length of labor, increased incidences of prolonged membrane rupture, oxytocin augmentation, arrest of descent, and vacuum extraction (8) (48).
Petechiae and ecchymoses: Observed in a newborn whose mother used raspberry leaf tea and evening primrose oil vaginally and orally 1 week before childbirth (12).
Lipoid pneumonia: In a 50-year-old woman following chronic use of evening primrose oil, caused by aspiration of lipid particles into the lungs (24).
Anticoagulants/Antiplatelets: May have additive effects and increase bleeding risk (46) (49). In a small study of humans on several months of supplementation with y-linoleic acid from evening primrose oil, a significant increase in bleeding time was observed in 9 of 12 patients (47). Evening primrose oil is about 10% GLA (52).
Blood pressure medications: Although there are no interactions reported with blood pressure medications, evening primrose oil was identified as being among supplements that may increase both systolic and diastolic blood pressures, with a clinically meaningful difference for systolic blood pressure in a large population-based study (50).
Antiretrovirals: In humans, evening primrose oil significantly increases the levels of antiretroviral drugs and may increase the risk of adverse effects (51).