Evening Primrose

Evening Primrose Oil (EPO) is a well-known botanical supplement extracted from the seeds of Oenothera biennis, valued for its high content of gamma-linolenic acid (GLA), an anti-inflammatory omega-6 fatty acid. 

Used traditionally for women's health and skin conditions, EPO continues to support inflammation, hormonal symptoms, and dermatologic concerns in integrative and clinical care.

What is Evening Primrose Oil?

Evening Primrose Oil (EPO) is a popular botanical supplement derived from the seeds of the Oenothera biennis plant. 

It is rich in gamma-linolenic acid (GLA), an omega-6 fatty acid that plays a vital role in modulating inflammation and supporting skin, hormonal, and immune health. 

Although not considered a biomarker or diagnostic tool, EPO is commonly used in clinical practice as an adjunct to support chronic inflammatory conditions, hormone-related symptoms, and skin disorders.

Evening Primrose Oil is extracted by cold-pressing the seeds of the evening primrose plant. Its primary active component is gamma-linolenic acid (GLA), which the body converts into dihomo-gamma-linolenic acid (DGLA)—a precursor to anti-inflammatory prostaglandins (especially PGE1). 

EPO has been used historically by Indigenous populations for wound healing and women’s health and is now widely available as a dietary supplement in capsule or liquid form.

Traditional Uses of Evening Primrose

Evening Primrose, also known as King’s cure-all, German rampion, or fever-plant, has a long history of traditional use among Native American tribes such as the Cherokee, Iroquois, Ojibwe, and Potawatomi. These communities used various parts of the plant both as food and medicine. 

The roots were boiled like potatoes, young leaves cooked as greens, and fresh shoots eaten raw. 

Medicinally, teas were made to support digestion and weight loss, while poultices from the root or whole plant were applied to bruises, boils, and piles. 

The roots were also used externally to reduce muscle pain and strengthen limbs, and internally to relieve menstrual and bowel pain.

Today, Evening Primrose is primarily cultivated for its oil, extracted from the seeds and rich in gamma-linolenic acid (GLA) and linoleic acid. These essential fatty acids contribute to its therapeutic reputation for managing skin conditions, hormonal symptoms, and inflammation. 

The plant itself is a tall, biennial herb with yellow, night-blooming flowers and is commonly found in dry fields, roadsides, and open woods across North America.

Who Should Consider Using Evening Primrose Oil?

EPO may benefit a variety of patient populations:

Individuals with Skin Conditions

Patients with atopic dermatitis (eczema), acne, and psoriasis may experience improvement in symptoms due to GLA’s role in enhancing skin barrier function and reducing inflammation.

Women with PMS or Menopausal Symptoms

Clinical use of EPO often centers around women’s health, particularly for easing breast tenderness, mood swings, and hot flashes.

Patients with Inflammatory Conditions

Due to its anti-inflammatory properties, EPO may provide modest benefit in rheumatoid arthritis (RA) and other autoimmune diseases, although current research cannot confirm its universal benefit.

Pregnant and Breastfeeding Women

While often marketed for use in late pregnancy to soften the cervix or ease labor, evidence is limited, and its use should be approached with caution. Clinicians should evaluate risks on a case-by-case basis.

Potential Benefits of Evening Primrose Oil

Evening primrose oil may be helpful for:

Skin Health

EPO is frequently used in dermatology for its effect on skin hydration and elasticity. 

Gamma-linolenic acid (GLA), particularly when consumed as part of a GLA-rich oil or supplement like evening primrose oil (EPO), has been shown to safely improve skin barrier function by reducing transepidermal water loss and epidermal hyperproliferation, especially in individuals with dry skin or mild atopic dermatitis.

Some research has shown improvement in skin roughness, scaling, and itching in eczema patients. Benefits may take up to 12 weeks to become noticeable.

Hormonal Balance

EPO is often included in integrative protocols for PMS and menopause. GLA-derived prostaglandins may help modulate hormonal signaling and reduce sensitivity to hormonal fluctuations. 

While studies are mixed, some show reductions in breast pain, irritability, and hot flash frequency.

Anti-Inflammatory Properties

GLA competes with arachidonic acid (AA) in inflammatory pathways, promoting anti-inflammatory prostaglandin E1 (PGE1) over pro-inflammatory PGE2. 

In rheumatoid arthritis, EPO supplementation has been associated with reduced joint tenderness and stiffness in at least one trial, though results are not universally consistent and may be attributed to other causes.

Risks and Side Effects of Evening Primrose Oil

EPO is generally well-tolerated, but clinicians should counsel patients on potential side effects, including:

• Mild gastrointestinal symptoms: nausea, bloating, or diarrhea.
• Headaches: reported in some individuals.
• Drug interactions: caution with anticoagulants or antiplatelet drugs due to potential additive effects.
• Seizure risk: there is a theoretical risk of lowering seizure threshold, especially in patients taking phenothiazines or with epilepsy.
• Prolonged bleeding: there is a theoretical risk that EPO can decrease platelet aggregation and prolong bleeding time.

Pregnant women should avoid unsupervised use of EPO, particularly in the first trimester, due to unknown fetal effects and potential influence on uterine contractility.

Dosage and Administration Guidelines

EPO is typically dosed based on its GLA content. Dosages range amongst research studies but may include:

• Skin conditions: 500–1,000 mg EPO (providing 40–100 mg GLA) 2–3 times daily.
• Women’s health: 1,000–3,000 mg daily.
• Rheumatoid arthritis: up to 2.8 grams per day, often combined with fish oil or other anti-inflammatory agents.

Always talk with your doctor before beginning any new supplement regimen and to determine the best dose for you. 

Benefits may take 2–3 months to become evident. Clinicians should re-evaluate after 12 weeks to determine ongoing need.