Termed commonly as "Kings cure-all", Oenothera biennis or evening primrose is a native biennial of the Onagraceae family. In the past, Native Americans used evening primrose as a treatment for bruises and cuts.

Inside the seed-extracted oil is where the medicinal components of evening primrose are found. This oil contains approximately 7-10% gamma-linolenic acid, which is an essential fatty acid that is often deficient in the Western diet. GLA is essential to the production of prostaglandins. When levels of essential fatty acids are low, symptoms of premenstrual syndrome (PMS), diabetes, etc may become increased.

For the above reasons, evening primrose oil has been a recommendation among many as a treatment for PMS and menopausal symptoms. High blood cholesterol levels have also been shown to be reduced with evening primrose oil.

One of the primary benefits of evening primrose oil is its antioxidant properties. In Canada, researchers recently found the specific antioxidant compounds in evening primrose oil. One of them includes catechin, which is a yellow substance that appears to inhibit the growth of cancerous tumors and lower the risk of heart disease.

Researchers in the United Kingdom have conducted studies which indicate that evening primrose oil may be beneficial in treating conditions such as multiple sclerosis and rheumatoid arthritis. When used in combination with zinc, this essential oil can also help relieve dry eyes, brittle nails, and acne. Supplementing with evening primrose has also been shown to help promote weight loss.

Evening primrose oil is available in most health food stores. It is also valuable in capsule form. For the most accurate dosage, consultation with a professional health care practitioner is recommended.