Evening primrose is a wildflower that grows throughout the United States. Although Native Americans used the seeds for food and made poultices from the whole plant to heal bruises, evening primrose oil (EPO) has only recently been used as medicine. European settlers took the root back to England and Germany where it was eaten as food.

EPO is found in the plant’s seeds, and is high in the essential fatty acid gamma-linolenic acid (GLA). Essential fatty acids, such as omega-6s found in EPO and omega-3s found in fish oil, are used as building blocks for a number of molecules in the body. Your body needs a balance of omega-6 and omega-3 fatty acids for good health.

Gamma-linolenic acid (GLA) is an omega-6 fatty acid. Omega-6 fatty acids are considered essential fatty acids. They are necessary for human health, but the body cannot make them. You have to get them through food. Along with omega-3 fatty acids, omega-6 fatty acids play a crucial role in brain function, and normal growth and development. Also known as polyunsaturated fatty acids (PUFAs), they help stimulate skin and hair growth, maintain bone health, regulate metabolism, and maintain the reproductive system.

Some studies show that taking gamma linolenic acid (GLA) for 6 months or more may reduce symptoms of nerve pain in people with diabetic neuropathy. People who have good blood sugar control may find GLA more effective than those with poor blood sugar control.

Studies are mixed as to whether EPO helps reduce symptoms of rheumatoid arthritis. Preliminary evidence suggests EPO may reduce pain, swelling, and morning stiffness. But other studies have found no effect. When using GLA for arthritis symptoms, it may take 1 to 3 months to see any benefit. It is unlikely that EPO would help stop the progression of the disease. So joint damage could still occur.

GLA from EPO or other sources has a longstanding history of folk use for allergies. Women and children who are prone to allergies appear to have lower levels of GLA in breast milk and blood. 

Clinical studies suggest that children with ADHD have lower levels of essential fatty acids (EFAs), both omega-6s and omega-3s. EFAs are important to normal brain and behavioral function. Some studies suggest that taking fish oil (containing omega-3 fatty acids) may help reduce ADHD symptoms..

One study found that women with breast cancer who took GLA had a better response to tamoxifen (a drug used to treat estrogen-sensitive breast cancer) than those who took only tamoxifen. 

Eczema symptoms include redness and scaling in addition to itching. More than 30 human studies report the benefits of EPO for eczema and dermatitis. A study of 1,207 people found that EPO helped relieve symptoms from skin conditions, including itching, crusting, edema (fluid retention and swelling), and redness. EPO can be used in children and adults with skin conditions.

Preliminary evidence suggests that GLA may help reduce high blood pressure, either alone or in combination with the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), found in fish oil. In one study, men with borderline high blood pressure who took 6g of GLA had a reduction in diastolic blood pressure compared to those who took placebo.

Another study examined people with intermittent claudication, pain in the legs while walking that is caused by blockages in the blood vessels. Those who took GLA combined with EPA had a reduction in systolic blood pressure compared to those who took placebo.

One small study suggests that taking EPO may help reduce symptoms in some people with Raynaud’s phenomenon. 

EPO has gained popularity as a way to treat hot flashes associated with menopause. Studies are mixed.

Some evidence suggests that EPO may reduce breast pain and tenderness in people with cyclic mastalgia. It may also help reduce symptoms to a lesser extent in people with noncyclic mastalgia. 

Some studies suggest that people who do not get enough essential fatty acids (particularly EPA and GLA) are more likely to have bone loss than those with normal levels of these fatty acids. In a study of women over 65 with osteoporosis, those who took EPA and GLA supplements had less bone loss over 3 years than those who took placebo. Many of these women also experienced an increase in bone density.

Although most studies have found no effect, some women report relief of PMS symptoms when using GLA. The symptoms that seem to improve the most are breast tenderness and feelings of depression, as well as irritability, swelling, and bloating from fluid retention.

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