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Evening Primrose Oil

What is evening primrose oil? Why do we need it?

Evening primrose oil comes from the seeds of the evening primrose plant.

Similar to borage oil, which is discussed elsewhere on this site, evening primrose oil's main ingredient is gamma linolenic acid, a type of fatty acid that the body converts to prostaglandin E1 (PGE1), a hormone-like substance essential for several chemical processes.

Evening primrose oil has been used primarily to treat diabetes and skin conditions such as itching, redness, eczema and dry skin. Evening primrose oil also acts as an anti-inflammatory, and may be useful in treating conditions such as rheumatoid arthritis. Some studies have shown that evening primrose oil may help reduce cholesterol levels in the blood and cause some cancerous tumors to shrink, but further research into these claims is warranted.

How much evening primrose oil should I take?

Because evening primrose oil is not an essential nutrient, recommended intake levels have yet to be established. However, most researchers have used between 3,000 and 6,000 milligrams of evening primrose oil in clinical trials, which translates to approximately 270 milligrams to 540 milligrams of gamma linolenic acid.

What forms of evening primrose oil are available?

The primary source of evening primrose oil is as a dietary supplement (usually a capsule or extract), which is derived from the seeds of the evening primrose plant. For the body to convert evening primrose into PGE1, several other nutrients are needed, including magnesium, zinc, vitamin C and vitamin B6. As a result, some health care providers recommend that these nutrients be taken in conjunction with evening primrose oil for optimal health and well-being.

What can happen if I take too much evening primrose oil? Are there any interactions I should be aware of? What precautions should I take?

Some studies have shown that evening primrose oil can bring about the symptoms of temporal lobe epilepsy. Patients taking medications for epileptic seizures should consult with their health care provider before taking evening primrose supplements. In addition, it may interfere with the activity of tamoxifen, a well-known breast cancer drug. As always, make sure to consult with a licensed health care provider before taking evening primrose oil or any other herbal remedy or dietary supplement.


  • Holman CP, Bell AFJ. A trial of evening primrose oil in the treatment of chronic schizophrenia. J Orthomol Psychiatr 1983;12:302-4.
  • Joe LA, Hart LL. Evening primrose oil in rheumatoid arthritis. Ann Pharmacother 1993;27:1475-7.
  • Keen H, Payan J, Allawi J, et al. Treatment of diabetic neuropathy with gamma-linolenic acid. Diabetes Care 1993;16:8-15.
  • Naidu MRC, Das UN, Kshan A. Intratumoral gamma-linolenic acid therapy of human gliomas. Prostaglandins Leukot Essent Fatty Acids 1992;45:181-4.
  • Yoshimoto-Furuie K, Yoshimoto K, Tanaka T, et al. Effects of oral supplementation with evening primrose oil for six weeks on plasma essential fatty acids and uremic skin symptoms in hemodialysis patients. Nephron 1999;81:151-9.
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