Oenothera biennis (Evening Primrose Oil)

Introduction

A biennial herb that grows to about 1 meter in height. The oil extracted from the seed contains about 60-80% linoleic acid plus 8-14% gamma-linolenic acid.

Uses

Current uses:

• premenstrual syndrome (especially mastalgia)
• atopic dermatitis
• diabetic neuropathy
• rheumatoid arthritis
• hot flashes (menopausal symptoms)*
• mastalgia

* not useful

Dosage

• 500 mg capsules
• 3 g/day commonly used
• optimal dose not known

Adverse effects

• nausea
• softening of stools
• headache
• may increase risk pregnancy complications

Drug interactions

• may increase risk of bleeding when used with warfarin

Mechanism of action

• active ingredients: gamma-linolenic acid
• patients with atopic dermatitis may be deficient in conversion of linoleic acid to gamma-linolenic acid
• the 1-series of prostaglandins formed using gamma-linolenic acid as substrates may have less inflammatory properties than the 2-series

More general terms

• pharmaceutical herb; medicinal herb; herbal supplement; botanical

Component of

• gamma linolenate/oenothera biennis
• linoleate/oenothera biennis
• bilberry/oenothera biennis
• bilberry/flax oil/oenothera biennis