evening primrose oil

What Is It?
Health Benefits
Dosage Information
Guidelines for Use
General Interaction
Possible Side Effects
Evidence Based Rating Scale

What Is It?

Evening primrose oil (EPO) is extracted from the evening primrose plant Oenothera biennis, a wildflower found in North America, Europe and parts of Asia. The plant's pale yellow flowers open in the evening--hence its common name--and its seeds bear the special fatty oil that is used in healing today.

In another era, Native Americans and the early settlers gathered the plant and its root to treat such ailments as hemorrhoids, stomach aches, sore throat, and bruises. It took modern research to unveil the therapeutic power contained within the seed oil: an essential fatty acid (EFA) called gamma-linolenic acid (GLA). Once processed in the body, GLA, an omega-6 fatty acid, exerts anti-inflammatory and other healing actions. The seeds also contain alpha-linolenic acid (ALA), an omega-3 fatty acid. (1) 

EPO is certainly not the only source of GLA; various foods actually contain small amounts of it and the body produces GLA on its own from a number of dietary fats. But EPO offers an unusually concentrated source, with 2% to 16% of its fatty acids available in the form of GLA. (2) Interestingly, borage oil features even more GLA (18% to 26%), and black currant oil offers rich stores as well (6% to 19%), but their effectiveness and safety for many ailments has not been as intensively examined as EPO. (3, 4) Nonetheless, some people prefer borage and black currant oils because a lower dose (at less total cost) provides the same amount of GLA. 

Health Benefits

The remarkably rich stores of GLA in EPO are what make it so valuable in healing. Taken internally, the body converts GLA into a form of prostaglandin. Prostaglandins are hormone-like compounds that help regulate various body functions that reduce inflammation in some cases and promote it in others. GLA produces the anti-inflammatory prostaglandin E1. Cell membranes also rely on the presence of GLA.

Specifically, EPO may help:

Help treat acne and rosacea. By working to dilute sebum, a thick oily substance that is over-secreted in some people with acne, the essential fatty acids (EFA) in EPO may reduce the risk of pores becoming clogged and lesions developing. The oil's EFAs help treat rosacea by reducing inflammation, controlling cells' use of nutrients, and by producing prostaglandins that stimulate the contraction of blood vessels. (5) 

Protect against the effects of aging. As the body ages, it loses its ability to convert dietary fats into GLA. Because this essential fatty acid is involved in so many body processes, taking EPO can help to compensate for any deficiencies in GLA. (6) EPO may also benefit wrinkles caused by UVB rays. In one study, female mice were orally administered a mixture of pycnogenol, vitamins C and E, and EPO for ten weeks. During this time, UVB rays were also administered three times a week. At the end of the study, wrinkle formation from UVB rays was significantly reduced in mice fed the Antioxidant mixture. Human studies are needed to confirm these results. (7) 

Prevent alcohol withdrawal symptoms. GLA prompts the brain to produce a specific type of prostaglandin called prostaglandin E, which works to prevent withdrawal symptoms such as depression and seizures by indirectly protecting the liver and nervous system. (8) 

Prevent diabetes-associated nerve damage. Research indicates that the GLA in EPO can help prevent--and in some cases even reverse--the nerve damage (neuropathy) so commonly seen with diabetes. In a year-long study, such symptoms as numbness, tingling, and loss of sensation in participants with mild Diabetic neuropathy were less marked in those who took EPO than in those who took a placebo. Further studies are needed to confirm EPO's efficacy. Additionally, patients should be advised that EPO can potentially interact with other drugs including blood thinners such as Coumadin and with Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) such as ibuprofen. (9, 10) 

Reduce the symptoms of eczema. In some cases, eczema develops when the body has problems converting dietary fats into GLA. Getting supplemental GLA from EPO may therefore be helpful. Some studies indicate that this oil can outperform a placebo in relieving eczema-related inflammation, as well as the itching, oozing, and flaking associated with this condition. By taking GLA, eczema sufferers may be able to reduce doses of steroid creams and drugs--many of which cause unpleasant side effects. Not all studies point to such benefits, however, and many conventional doctors remain skeptical. (11) 

Counter impotence and female infertility. In a 2001 animal study, EPO and alpha linolenic acid both improved blood flow and nerve function in diabetic rats. (12)  By promoting blood flow, the GLA in EPO may help treat a primary cause of male impotence--compromised circulation leading to impaired penile blood flow. However, in the same study, EPO was associated with increased triglyceride levels and decreased HDL ("good") cholesterol levels. Studies are needed in humans before EPO can be recommended for impotence. Animal studies with female ewes indicated that GLA increased the production of endometrial and placental prostaglandins, which regulate cell function. However, human studies are needed to determine if GLA has a similar effect on female fertility. (13) 

Alleviate inflammation associated with lupus. Inflammation in the kidneys, joints, skin, and other areas of the body caused by the condition known as Systemic Lupus Erythematosus (SLE) may subside as a result of EPO’s anti-inflammatory actions. Taking the oil may lower elevated cholesterol levels in those suffering from lupus as well. (14) 

Nourish nails, scalp, and hair. In one study, 500mg of EPO was administered to healthy adults three times a day for twelve weeks. At the end of the study, the participants showed improvements in skin moisture, roughness, firmness, and elasticity. (15) This study also suggests that the essential fatty acids in EPO may prevent nails from cracking and help keep them generally healthy. In addition, the essential fatty acids nourish the scalp, making the supplement potentially valuable in treating a variety of hair problems. 

Benefit osteoporosis. In a pilot study, sixty-five women (average age 79.5) with a background diet low in calcium were given a combination of GLA with EPA or a coconut oil placebo along with 600mg/day of calcium for a period of eighteen months. The combination of GLA, EPA, and calcium seemed to decrease bone turnover and increase bone mineral density in the spine and femur. (16) More studies are needed to confirm or refute these findings.  

Relieve the discomforts of premenstrual syndrome (PMS), menopause symptoms, and cyclic breast pain. In a 2009 review of studies, no evidence was found to support the use of EPO for the overall symptoms of PMS. (17) However, a 2010 pilot study indicated EPO was effective for relieving premenstrual breast pain. In this study, eighty-five women with premenstrual cyclical breast discomfort were randomly assigned supplements of vitamin E, EPO, a combination of the two, or placebo. After six months, all supplement groups reported reduction in breast pain compared to placebo. (18) EPO has also been used to alleviate the hot flashes associated with menopause. In one small study, EPO alleviated nighttime hot flashes but had no effect on daytime hot flashes. (19) However, the evidence to support this use is limited; more studies are needed. (20)

Ease the joint pain and swelling of rheumatoid arthritis. Supplementation with EPO and other sources of GLA has been shown to lessen the joint pain and swelling of this crippling disease. A six-month study reported fewer signs of inflammation in rheumatoid arthritis sufferers taking capsules containing GLA than in those taking a Placebo. (21) However, larger studies are needed to recommend EPO as a treatment for rheumatoid arthritis.

Note: EPO has also been found to be useful for a number of other disorders. For information on these additional ailments, see our Dosage Recommendations Chart for Evening Primrose Oil.


  • capsule
  • oil
  • softgel

Dosage Information

For most of the ailments mentioned: Take 1,000 mg EPO three times a day. This provides 240 mg of GLA over the course of a day.

Special tip:  Equivalent amounts of GLA (240 mg a day) can be obtained from daily dosages of 1,000 mg of borage oil or 1,500 mg of black currant oil.

  • For acne: Take 1,000 mg EPO three times a day

  • For aging: Take 1,000 mg EPO three times a day

  • For alcohol withdrawal symptoms: Take 1,000 mg EPO three times a day

  • For diabetes: Take 1,000 mg EPO three times a day, along with 1,000 mg of fish oils twice a day

  • For eczema: Take 1,000 mg EPO three times a day

  • For lupus: Take 1,000 mg EPO three times a day

  • For hot flashes associated with menopause: Take 500 mg EPO four times a day

  • For nail and skin health: Take 500 mg EPO three times a day

  • For osteoporosis: Take 1,000 mg EPO three times a day

  • For premenstrual breast pain: Take 1,000 mg EPO three times a day

  • For rheumatoid arthritis: Take 1,000 mg EPO three times a day

  • For rosacea: Take 1,000 mg EPO three times a day

Be sure to check out our Dosage Recommendations Chart for Evening Primrose Oil, which lists therapeutic dosages for specific ailments at a glance.

Guidelines for Use

  • By taking EPO (or other GLA sources) with food, you will not only help ensure good absorption of GLA but possibly minimize any unpleasant side effects.

  • Be sure to buy EPO from a reliable manufacturer; cheap substitutes such as soy and safflower oils have been found in some commercial products.

  • Particularly when treating PMS and related discomforts, it's important to ensure proper conversion of EPO into GLA by taking it with a high-quality multi-vitamin/mineral (it should contain zinc, vitamin C, vitamin B-complex and magnesium).

  • A small amount of vitamin E added to EPO products reportedly slows the rather rapid breakdown of important fatty acids; opt for vitamin E-enhanced products when possible.

  • It may take two to six months to see effects for skin, hair and nail problems.

General Interaction

  • EPO may increase the risk of temporal lobe epilepsy in schizophrenic patients taking phenothiazine epileptogenic drugs.

  • EPO may have anticoagulant properties and could increase the risk of bruising and bleeding when combined with anticoagulant or antiplatelet drugs and herbs. Some of these include aspirin, heparin, warfarin, naproxen, non-steroidal anti-inflammatory drugs (NSAIDs),  clove, garlic, ginger, and others. Do not take EPO with any of these drugs and herbs. 

Note: For information on interactions with specific generic drugs, see our WholeHealthMD Drug/Nutrient Interactions Chart.

Possible Side Effects

  • Bloating or abdominal upset developed in a small percentage (about 2%) of those participating in EPO studies.  

Be sure to check out our Dosage Recommendations Chart for Evening Primrose Oil, which lists therapeutic dosages for specific ailments at a glance.


Data to support the safety of long-term use of EPO are not available. However, there have been few or no reports of toxic reactions to EPO over nearly two decades of widespread use as a supplement. In the United Kingdom, it is approved for the treatment of pre-menstrual breast tenderness and eczema. EPO may increase the risk of pregnancy complications including delayed rupture of the amniotic sac and failure of the fetus to descend into the birth canal. (22) Do not take evening primrose oil while pregnant. 


1. Philip HA. Hot flashes--a review of the literature on alternative and complementary treatment approaches. Altern Med Rev. 2003 Aug;8(3):284-302.
2. Kleijnen J. Evening primrose oil. BMJ 1994;309:824-825.
3. Fan YY, Chapkin RS. Importance of dietary gamma-linolenic acid in human health and nutrition. J Nutr 1998;128:1411-4.
4. Wu D, Meydani M, Leka LS, et al. Effect of dietary supplementation with black currant seed oil on the immune response of healthy elderly subjects. Am J Clin Nutr 1999;70:536-43.
5. Downing DT, Stewart ME, Wertz PW, Strauss JS. Essential fatty acids and acne. J Am Acad Dermatol. 1986 Feb;14(2 Pt 1):221-5.
6. Horrobin DF. Loss of delta-6-desaturase activity as a key factor in aging. Med Hypotheses. 1981 Sep;7(9):1211-20.
7. Cho HS, Lee MH, Lee JW, No KO, Park SK, Lee HS, Kang S, Cho WG, Park HJ, Oh KW, Hong JT. Anti-wrinkling effects of the mixture of vitamin C, vitamin E, pycnogenol and evening primrose oil, and molecular mechanisms on hairless mouse skin caused by chronic ultraviolet B irradiation. Photodermatol Photoimmunol Photomed. 2007 Oct;23(5):155-62.
8. Horrobin DF. Essential fatty acids, prostaglandins, and alcoholism: an overview. Alcohol Clin Exp Res. 1987 Feb;11(1):2-9.
9. Cameron NE, Cotter MA. Metabolic and vascular factors in the pathogenesis of diabetic neuropathy. Diabetes. 1997 Sep;46 Suppl 2:S31-7.
10. Halat KM, Dennehy CE. Botanicals and dietary supplements in diabetic peripheral neuropathy. J Am Board Fam Pract. 2003 Jan-Feb;16(1):47-57.
11. Morse NL, Clough PM. A meta-analysis of randomized, placebo-controlled clinical trials of Efamol evening primrose oil in atopic eczema. Where do we go from here in light of more recent discoveries? Curr Pharm Biotechnol. 2006 Dec;7(6):503-24.
12. Ford I, Cotter MA, Cameron NE, Greaves M. The effects of treatment with alpha-lipoic acid or evening primrose oil on vascular hemostatic and lipid risk factors, blood flow, and peripheral nerve conduction in the streptozotocin-diabetic rat. Metabolism. 2001 Aug;50(8):868-75.
13. Wathes DC, Abayasekara DR, Aitken RJ. Polyunsaturated fatty acids in male and female reproduction. Biol Reprod. 2007 Aug;77(2):190-201. Epub 2007 Apr 18.
14. Brown AC. Lupus erythematosus and nutrition: a review of the literature. J Ren Nutr. 2000 Oct;10(4):170-83.
15. Muggli R. Systemic evening primrose oil improves the biophysical skin parameters of healthy adults. Int J Cosmet Sci. 2005 Aug;27(4):243-9.
16. Kruger MC, Coetzer H, de Winter R, et al. Calcium, gamma-linolenic acid and eicosapentaenoic acid supplementation in senile osteoporosis. Aging (Milano) 1998;10:385-94.
17. Whelan AM, Jurgens TM, Naylor H. Herbs, vitamins and minerals in the treatment of premenstrual syndrome: a systematic review. Can J Clin Pharmacol. 2009 Fall;16(3):e407-29. Epub 2009 Oct 29.
18. Pruthi S, Wahner-Roedler DL, Torkelson CJ, Cha SS, Thicke LS, Hazelton JH, Bauer BA. Vitamin E and evening primrose oil for management of cyclical mastalgia: a randomized pilot study. Altern Med Rev. 2010 Apr;15(1):59-67.
19. Chenoy R, Hussain S, Tayob Y, et al. Effect of oral gamolenic acid from evening primrose oil on menopausal flushing. BMJ 1994;308: 501-503.
20. Carroll DG. Nonhormonal therapies for hot flashes in menopause. Am Fam Physician. 2006 Feb 1; 73(3):457-64.
21. Zurier RB, Rossetti RG, Jacobson EW, et al. Gamma-linolenic acid treatment of rheumatoid arthritis: a randomized, placebo-controlled trial. Arthritis Rheum 1996;39:1808–17.
22. Dove D, Johnson P. Oral evening primrose oil: its effect on length of pregnancy and selected intrapartum outcomes in low-risk nulliparous women (abstract). J Nurse Midwifery 1999;44: 320-4.

Evidence Based Rating Scale

The Evidence Based Rating Scale is a tool that helps consumers translate the findings of medical research studies and what our clinical advisors have found to be efficacious in their personal practice into a visual and easy to interpret format. This tool is meant to simplify the information on supplements and therapies that demonstrate promise in the treatment of certain conditions.









May reduce the risk of clogged pores by diluting sebum; studies are needed. (5)



May provide GLA as the body loses the ability to convert dietary fats; studies are needed. (6)

Alcoholism   Date Published: 04/18/2005
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