Friday, December 11, 2009

Medicinal Herbs: Evening Primrose Oil

Evening primrose oil


Evening primrose is a wildflower that grows throughout the U.S., and has served as food and medicine throughout history, often for upset stomach and respiratory infections. The oil is found in the plant's seeds and is high in the essential fatty acid gamma-linolenic acid (GLA). 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.

Plant Description

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. The leaves grow on both sides of the stem at alternating levels. This monograph focuses on the seed from which the oil is extracted.

What's It Made Of?

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. However, there are different types of omega-6 fatty acids. Some are health promoting, such as those found in evening primrose oil (EPO), while others can be more harmful, such as those typically found in the standard American 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, as well as some plant sources, or in dietary supplements.

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

Medicinal Uses and Indications

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:


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


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 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 with skin conditions.


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


Clinical trials of EPO for arthritis began in the early 1980s. 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 show 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 promotes health. 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.

Available Forms

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.

How to Take It

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.


For skin rash, the recommended total daily dosage for children is 2 - 4 grams (in capsule form), standardized to contain 8% GLA. Talk to your health care provider before putting your child on an EPO regimen.


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.

EPO should not be taken if you have bleeding problems or a blood disorder.

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

Possible Interactions

EPO may alter the effects of some prescription and nonprescription 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.

Other Possible Interactions -- Nonsteroidal anti-inflammatory drugs, anticoagulant and antiplatelet medicines and herbs with blood-thinning effects.

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