Evening primrose has served as food and medicine at throughout history, often for upset stomach and respiratory infections. Native Americans ate the boiled, nutty-flavored root, and used leaf poultices from the plant for bruises and hemorrhoids. European settlers took the root back to England and Germany, where it was introduced as food and became known as German rampion because it grew as a crawling vine. The plant was also a Shaker medicine, sold commercially.

A circle of leaves grows close to the ground around evening primrose stems after the first year it is planted. Flowers bloom after sunset, June through September, or on overcast days during the second year. Stems are branched, with alternate leaves (in other words, the leaves grow on both sides of the stem at alternating levels). This monograph focuses on the seed from which the oil is extracted.

Oil is extracted from the seeds and prepared as medicine using a chemical called hexane. The seeds contain up to 25% essential fatty acids including linoleic acid (LA) and gamma-linolenic acid (GLA). Both LA and GLA belong to the omega-6 family of fatty acids. The vast majority of North Americans get too much omega-6 fatty acid in their diet. The body needs a balance of omega-3 and omega-6 fatty acids to function normally. Omega-3 oils can be found in cold water fish such as salmon or in dietary supplements.

Other sources of GLA include spirulina (a blue-green algae), borage, hemp, and black currant oils.

Today, evening primrose seed oil (EPO) is used primarily to relieve the itchiness associated with certain skin conditions (such as eczema and dermatitis) and to ease breast tenderness from premenstrual syndrome (PMS) or other causes. Some of the uses for EPO include:

Allergies

EPO has been reported effective for rashes, particularly skin rash or hives (itching).

Eczema

Eczema symptoms include redness and scaling in addition to itching. There are over 30 positive human studies reporting benefits in eczema and dermatitis when using EPO. A review of including 1,207 patients reported that EPO was beneficial for skin conditions, including itching, crusting, edema (fluid, swelling), and redness. EPO can be used in children and adults for skin conditions.

PMS

EPO can help with symptoms of PMS, including mood swings, bloating, and breast tenderness.

Arthritis

Clinical trials of EPO for arthritis began in the early 1980s, focusing over the following years on patients with rheumatoid arthritis (RA). Available research has not demonstrated consistent support for arthritis, and currently there is not adequate evidence to recommend for or against this use of EPO.

Diabetic Neuropathy

Diabetic neuropathy is a nerve condition caused by diabetes. Patients experience numbness, tingling, pain, burning, or lack of sensation in the feet and legs. EPO may be beneficial in reducing these symptoms.

Breast Pain

EPO is officially licensed for the treatment of breast pain (mastalgia) in the United Kingdom and considered first-line therapy in several European countries. EPO was found effective at decreasing breast pain in several clinical studies, however, other studies report no benefit.

Menopausal symptoms

Although EPO has gained some popularity for treating hot flashes, the research to date has not confirmed that GLA or EPO is beneficial for these symptoms.

Other uses

• Breast cancer and breast cysts
• Multiple sclerosis
• Heart disease
• Raynaud's disease
• Chronic fatigue syndrome
• Pregnancy-induced hypertension (pre-eclampsia)
• Attention deficit/hyperactivity disorder (ADHD)
• Asthma

It is the balance of omega-6 (such as GLA) and omega-3 (such as fish oil) that helps keep a body healthy. Taking an omega-3 fatty acid supplement along with EPO may be more beneficial for health than EPO alone in these and other conditions.

The main active ingredient in EPO is an omega-6 fatty acid known as gamma-linolenic acid (GLA). See What's It Made Of section.

Evening primrose oil (EPO) is available as an oil or in capsules. EPO products should be kept in the refrigerator and out of direct sunlight to prevent the oil from becoming rancid. Generally, high-quality oil will be certified as organic by a reputable third party, packaged in light-resistant containers, refrigerated, and marked with a freshness date.

EPO should be standardized to contain 8% gamma-linolenic acid.

The use of herbs is a time-honored approach to strengthening the body and treating disease. Herbs, however, contain components that can trigger side effects and that can interact with other herbs, supplements, or medications. For these reasons, herbs should be taken with care, under the supervision of a health care provider qualified in the field of botanical medicine.

Pediatric

For skin rash, the recommended total daily dosage for children is 2 - 4 grams (in capsule form), standardized to contain 8% GLA.

Adult

Take 2 - 8 grams of EPO daily, standardized to contain 8% GLA. Higher dosages are used for more severe health needs. Ask your health care provider for the appropriate dosage to help your condition.

EPO is generally safe when used in recommended dosages. Reported side effects are rare and mild, and include nausea, stomach pain, and headache. Stomach pain and loose stools may be indications that the dosage is too high.

Omega-6 supplements, including GLA and EPO, should not be used if you have a seizure disorder because there have been reports of these supplements inducing seizures.

Taking EPO while breastfeeding is considered safe as breast milk actually contains both LA and GLA.

Evening primrose oil (EPO) may alter the effects of some prescription and non-prescription medications. If you are currently being treated with any of the following medications, you should not use EPO without first talking to your health care provider.

Phenothizines -- Individuals taking a class of medications called phenothiazines (such as chlorpromazine, fluphenazine, perphenazine, promazine, and thioridazine) to treat schizophrenia should not take EPO because it may interact with these medications and increase the risk of seizures.

al-Sabanah OA. Effect of evening primrose oil on gastric ulceration and secretion induced by various ulcerogenic and necrotizing agents in rats. Food Chem Toxicol. 1997;35(8):769-775.

Aman MG, Mitchell EA, Turbott SH. The effects of essential fatty acid supplementation by Efamol in hyperactive children. J Abnorm Child Psychol. 1987;15(1):75-90

Barre DE. Potential of evening primrose, borage, black currant, and fungal oils in human health. Annals of Nutrition & Metabolism. 2001;45(2):47-57.

Belch JJ, Hill A. Evening primrose oil and borage oil in rheumatologic conditions. Am J Clin Nutr. 2000;71(1 Suppl):352S-356S.

Birch AE, Fenner GP, Watkins R, Boyd LC. Antioxidant properties of evening primrose seed extracts. J Agric Food Chem. 2001;49(9):4502-7.

Burgess J, Stevens L, Zhang W, Peck L. Long-chain polyunsaturated fatty acids in children with attention-deficit hyperactivity disorder. Am J Clin Nutr. 2000; 71(suppl):327S-330S.

Calder PC, Miles EA. Fatty acids and atopic disease. Pediatr Allergy Immunol. 2000;11 Suppl 13:29-36.

Calder PC, Zurier RB. Polyunsaturated fatty acids and rheumatoid arthritis. Curr Opin Clin Nutr Metab Care. 2001;4(2):115-121.

Chenoy R, Hussain S, Tayob Y, O'Brien PM, Moss MY, Morse PF. Effect of oral gamolenic acid from evening primrose oil on menopausal flushing. BMJ. 1994;19(308):501-503.

Darlington LG, Stone TW. Antioxidants and fatty acids in the amelioration of rheumatoid arthritis and related disorders. Br J Nutr. 2001;85(3):251-269.

Davies CL, Loizidou M, Cooper AJ, et al. Effect of gamma-linolenic acid on cellular uptake of structurally related anthracyclines in human drug sensitive and multidrug resistant bladder and breast cancer cell lines. Eur J Cancer. 1999;35:1534-1540.

De La Cruz JP, Martin-Romero M, Carmona JA, Villalobos MA, Sanches DC. Effect of evening primrose oil on platelet aggregation in rabbits fed an atherogenic diet. Thromb Res. 1997;87(1):141-149.

De La Cruz JP, Quintero L, Galvez J, Villalobos MA, Sanchez DC. Antioxidant potential of evening primrose oil administration in hyperlipemic rabbits. Life Sciences. 1999;65(5):543-555.

Fan YY, Chapkin RS. Importance of dietary gamma-linolenic acid in human health and nutrition. J Nutr. 1998; 128(9): 1411-1414.

Garcia CM, et al. Gamma linolenic acid causes weight loss and lower blood pressure in overweight patients with family history of obesity. Swed J Biol Med. 1986;4:8-11.

Graham-Brown R. Atopic dermatitis: unapproved treatments or indications. Clin Dermatol. 2000;18(2):153-158.

Halat KM, Dennehy CE. Botanicals and dietary supplements in diabetic peripheral neuropathy. J Am Board Fam Pract. 2003;16(1):47-57.

Hederos CA, Berg A. Epogam evening primrose oil treatment in atopic dermatitis and asthma. Arch Dis Child. 1996;75(6):494-497.

Hornych A, Oravec S, Girault F, Forette B, Horrobin DF. The effect of gamma-linolenic acid on plasma and membrane lipids and renal prostaglandin synthesis in older subjects. Bratisl Lek Listy. 2002;103(3):101-7.

Horrobin DF. Essential fatty acid metabolism and its modification in atopic eczema. Am J Clin Nutr. 2000;71(1 Suppl):367S-72S.

Horrobin DF. The role of essential fatty acids and prostaglandins in the premenstrual syndrome. J Reprod Med. 1983;28(7):465-468.

Keen H, Payan J, AllawiJ, et al. Treatment of diabetic neuropathy with gamma-linolenic acid. The Gamma-Linolenic Acid Multicenter Trial Group. Diabetes Care. 1993;16(1):8-15.

Kenny FS, Pinder SE, Ellis IO et al. Gamma linolenic acid with tamoxifen as primary therapy tn breast cancer. Int J Cancer. 2000;85:643-648.

Kollias J, Macmillan RD, Sibbering DM, Burrell H, Robertson JF. Effect of evening primrose oil on clinically diagnosed fibroadenomas. Breast. 2000;9(1):35-6.

LaValle JB, Krinsky DL, Hawkins EB, et al. Natural Therapeutics Pocket Guide. Hudson, OH:LexiComp; 2000: 430-431.

Little C, Parsons T. Herbal therapy for treating rheumatoid arthritis. Cochrane Database Syst Rev. 2001;(1):CD002948.

Menendez JA, del Mar Barbacid M, Montero S, et al. Effects of gamma-linolenic acid and oleic acid on paclitaxel cytotoxicity in human breast cancer cells. Eur J Cancer. 2001;37:402-413.

Morse PF, Horrobin DF, Manku MS, et al. Meta-analysis of placebo-controlled studies of the efficacy of Epogram in the treatment of atopic eczema: relationship between plasma essential fatty changes and treatment response. Br J Dermatol. 1989;121(1):75-90.

Rosolowich V, Saettler E, Szuck B, et al., Mastalgia. J Obstet Gynaecol Can. 2006;28(1):49-57.

Simopoulos AP. Essential fatty acids in health and chronic disease. Am J Clin Nutr. 1999;70(3 suppl):560S-569S.

Stoll BA. Breast cancer and the Western diet: role of fatty acids and antioxidant vitamins. Eur J Cancer. 1998;34(12):1852-1856.

Thompson L, Cockayne A, Spiller RC. Inhibitory effect of polyunsaturated fatty acids on the growth of Helicobacter pylori: a possible explanation of the effect of diet on peptic ulceration. Gut. 1994;35(11):1557-1561.

Whitaker DK, Cilliers J, de Beer C. Evening primrose oil (Epogam) in the treatment of chronic hand dermatitis: disappointing therapeutic results. Dermatology. 1996;193(2):115-120.

Williams HC. Evening primrose oil for atopic dermatitis. BMJ. 2003;327(7428):1358-9.

Worm M, Henz BM. Novel unconventional therapeutic approaches to atopic eczema. Dermatology. 2000;201(3):191-195.

Yoon S, Lee J, Lee S. The therapeutic effect of evening primrose oil in atopic dermatitis patients with dry scaly skin lesions is associated with the normalization of serum gamma-interferon levels. Skin Pharmacol Appl Skin Physiol. 2002;15(1):20-5.