Evening Primrose Oil

Medically reviewed by Prof. Giorgi Pkhakadze, MD, MPH, PhD — GMJ Editorial Board

What is Evening Primrose Oil?

Evening primrose oil (EPO) is extracted from the seeds of Oenothera biennis, a wildflower native to North America. This oil is particularly valued for its high concentration of gamma-linolenic acid (GLA), an omega-6 fatty acid that comprises 8-10% of the oil’s content. GLA is considered a “good” omega-6 fatty acid because it has anti-inflammatory properties, unlike many other omega-6 fats that can promote inflammation.

Evening primrose oil has been used traditionally by Native Americans for various health purposes and gained popularity in modern supplement form during the 1980s. Today, it’s commonly available in softgel capsules and is marketed primarily for women’s health concerns, skin conditions, and inflammatory issues.

Health benefits & uses

Moderate evidence:

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• Atopic dermatitis (eczema): Several studies suggest EPO may help reduce inflammation and improve skin barrier function in people with eczema, though results have been mixed
• Diabetic neuropathy: Some research indicates GLA supplementation may help reduce nerve pain and improve nerve function in diabetic patients

Limited evidence:

• Premenstrual syndrome (PMS): Despite popular use, scientific evidence for EPO’s effectiveness in treating PMS symptoms remains inconclusive
• Menopause symptoms: Limited studies show mixed results for hot flash reduction and other menopausal complaints
• Rheumatoid arthritis: Some small studies suggest potential anti-inflammatory benefits, but more research is needed
• Breast pain: Preliminary research suggests possible benefits for cyclical breast pain, though evidence is not strong

How it works

Evening primrose oil works primarily through its gamma-linolenic acid content. GLA is converted in the body to dihomo-gamma-linolenic acid (DGLA), which then produces anti-inflammatory compounds called prostaglandins, particularly prostaglandin E1 (PGE1). This pathway helps reduce inflammation and may modulate immune responses.

Unlike most omega-6 fatty acids that promote inflammation, GLA has the unique ability to produce anti-inflammatory mediators. This occurs because GLA bypasses a rate-limiting enzyme (delta-6-desaturase) that often becomes less efficient with age, illness, or poor nutrition. By providing GLA directly, EPO supplements can help maintain adequate levels of beneficial anti-inflammatory compounds.

Dosage

There is no established Recommended Daily Allowance (RDA) or Tolerable Upper Limit (UL) for evening primrose oil. Typical dosages used in research and clinical practice include:

• General use: 500-1,300 mg daily, usually divided into 2-3 doses
• Eczema: 2-8 grams daily (providing 160-640 mg GLA)
• Diabetic neuropathy: 480-720 mg GLA daily
• Premenstrual symptoms: 1-3 grams daily

Most supplements contain 8-12% GLA, so a 1,000 mg capsule typically provides 80-120 mg of GLA. It’s recommended to take EPO with food to improve absorption and reduce potential stomach upset. Always consult with a healthcare provider before starting supplementation, especially for therapeutic doses.

Food sources

Evening primrose oil is not naturally present in common foods. The primary dietary sources of GLA include:

• Borage oil: Contains the highest concentration of GLA (20-25%)
• Black currant seed oil: Contains 15-20% GLA
• Hemp seed oil: Contains 2-5% GLA
• Spirulina: Contains small amounts of GLA

Since GLA is not abundant in typical Western diets, supplementation is the most practical way to obtain therapeutic amounts. Evening primrose oil supplements remain the most studied and widely available source of this beneficial fatty acid.

Safety & side effects

Evening primrose oil is generally well-tolerated by most people when used appropriately. Common mild side effects may include:

• Stomach upset or nausea
• Headache
• Soft stools or diarrhea
• Bloating or gas

Taking EPO with food can help minimize gastrointestinal side effects. Most adverse effects are dose-dependent and typically resolve when the dosage is reduced or discontinued.

Interactions

Drug interactions:

• Anticoagulant medications: EPO may increase bleeding risk when combined with warfarin, aspirin, or other blood thinners
• Seizure medications: May potentially lower seizure threshold in people taking phenothiazines or other seizure-related medications

Supplement interactions:

• Fish oil: Generally safe to combine, but monitor for excessive bleeding
• Vitamin E: Often included in EPO supplements to prevent oxidation; synergistic relationship

Who should be cautious

Certain individuals should exercise caution or avoid evening primrose oil:

• People with bleeding disorders: EPO may increase bleeding risk
• Those scheduled for surgery: Discontinue at least 2 weeks before surgical procedures
• Individuals with epilepsy or seizure disorders: May potentially lower seizure threshold
• Pregnant and breastfeeding women: Safety during pregnancy is not well-established
• People taking blood-thinning medications: Requires medical supervision

Frequently asked questions

How long does it take for evening primrose oil to work?

Effects typically become noticeable after 6-8 weeks of consistent use, as it takes time for fatty acid levels to change in cell membranes. Some people may notice improvements in skin conditions within 4-6 weeks, while benefits for inflammatory conditions may take 2-3 months to become apparent.

Can men take evening primrose oil?

Yes, men can benefit from EPO supplementation. While it’s often marketed for women’s health, the anti-inflammatory properties of GLA can benefit anyone dealing with inflammatory conditions, eczema, or inadequate essential fatty acid intake.

Should evening primrose oil be taken with other supplements?

EPO works well with vitamin E (which helps prevent oxidation) and can be combined with omega-3 supplements for a balanced fatty acid profile. However, be cautious when combining with other supplements that affect blood clotting.

Is evening primrose oil better than other GLA sources?

While borage oil contains higher GLA concentrations, evening primrose oil has been more extensively studied and is generally considered safer. The choice depends on individual needs, tolerance, and the specific condition being addressed.

Can evening primrose oil help with weight loss?

There is no strong scientific evidence that EPO directly promotes weight loss. While some people report appetite changes, weight loss is not a proven benefit of evening primrose oil supplementation.