Scientific Names of Evening Primrose Oil:    

Oenothera biennis L. [Fam. Onagraceae]


Certified organic EPO, expeller-pressed in the absence of light, heat and oxygen; standardized GLA (Gamma-Linolenic Acid) EPO

Traditional Usage:

– Allergies
– Anti-inflammatory
– Antioxidant (indirect)
– Attention Deficit and Hyperactivity Disorder (ADHD)
– Autoimmune Diseases
– Bone and Joint Health
– Brain Disorders
– Breathing Disorders
– Cellular Regeneration
– Chronic Fatigue Syndrome
– Cyclic Mastalgia/Mastitis
– Dyslexia/dyspraxia/dyskinesia
– Eczema
– EFA Deficiency
– Endometriosis
– Eyesight Disorders
– Fatigue
– Fibrocystic Breast Disease
– Fibroids
– Fibromyalgia
– Hemorrhoids
– Hormone Imbalances
– Joint Pain
– Menopausal Problems
– Muscle Cramps/Pain
– Multiple Sclerosis
– Nervous Disorders
– Neuropathy, diabetic
– Osteoporosis
– Raynaud’s Disease
– Reproductive Organ Health
– Retinal Disorders
– Senility/Aging Problems
– Skin Disorders
– Ulcerative Colitis
– Urinary System Stones
– Weight Loss


Evening Primrose Oil products consist of the oil of dried, ripe seed of Oenothera biennis L. [Fam. Onagraceae]. Evening primrose oil is a good source of Gamma-Linolenic Acid (GLA), a biologically important fatty acid normally produced within the human body from enzymatic conversion of linoleic acid (omega-6 EFA) into its longer-chain derivatives. EFAs are “good” fats that are precursors to various prostaglandins and leukotrienes – and are as necessary for health as vitamins. GLA is associated with beneficial anti-inflammatory prostaglandins. GLA is also a precursor for dihomogamma-linolenic acid, found concentrated in human breast milk. The myriad health benefits of GLA are well established, including its role in hormone balance. Prostaglandins and leukotrienes influence inflammation and pain so having the right balance of precursor EFA’s in the diet can be critical for avoiding inflammatory diseases. Having an excess of bad fats in the diet, such as trans fats or unnatural hydrogenated fats, can disrupt enzyme pathways needed to convert the precursor EFAs to their important metabolites and this can increase pain and inflammation. Taking GLA helps to swing the balance over to the more favorable prostaglandins and leukotrienes, making it helpful for diseases that involve inflammation. Clinical trials have demonstrated benefits with GLA for treating diabetic neuropathy, infantile atopic eczema, mastalgia, bone and joint conditions, osteoporosis, schizophrenia and postviral fatigue syndrome. GLA is widely used in Europe to treat diabetic neuropathy and eczema. Both European and U.S. physicians use GLA to treat cyclic mastalgia, a condition marked by breast pain associated with the menstrual cycle. GLA is also useful for reducing irritability and other PMS symptoms and is frequently recommended by medical doctors in Canada and the U.S. for women experiencing pre- and post-menopausal difficulties.

Active Ingredients:  

The natural clear yellow to yellow-green oil contains: Fatty acids with not less than 8% gamma-linolenic acid (GLA). The peroxide value should be less than 10 meq/kg oil and free fatty acids should be less than 10 mg KOH/g.

Suggested Amount:    

For GLA supplementation: Take 2000 – 4000mg of Evening Primrose Oil daily corresponding to 200 to 400 mg daily of GLA used to treat cyclic mastalgia or eczema (about 2 to 4 g of evening primrose oil). Diabetic neuropathy is typically treated with about 400 to 600 mg GLA daily (about 4 to 6 g of evening primrose oil) and bone and joint conditions may require as much as 2,000 to 3,000 mg of GLA. GLA should be taken with food. Benefits may be experienced immediately or may take over 6 months to develop.

Drug Interactions:   

There are no known drug interactions with evening primrose oil.


Early reports suggested that GLA might worsen temporal lobe epilepsy but this has not been confirmed. The maximum safe dosage of GLA for young children, pregnant or nursing women, or those with severe liver or kidney disease has not been established. Because GLA is not a normal dietary component, it is best to take the precursor EFAs in these cases and avoid bad fats to optimize the body’s own natural GLA production.

Side Effects:    

Taken as directed, EPO does not have any noted negative side effects. Over 4,000 people have taken GLA from evening primrose oil in scientific studies, and no significant adverse effects have been noted. Animal studies suggest that evening primrose oil is completely nontoxic and non-carcinogenic.


Briggs, C.J. 1986. Evening Primrose: La Belle de Nuit, the King’s Curall. Canadian Pharmaceutical J. 119: (5): 249-254.

Duke, J. A. 1988. Evening Primrose: The Morning After. Let’s Live 56 (7): 56-57

Gately et al. 1992: Drug treatments for mastalgia: 17 years experience in the Cardiff Mastalgia Clinic. J R Soc Med 85(1):12-15

Keen et al. 1993: Treatment of diabetic neuropathy with gamma-linolenic acid. The gamma-linolenic acid multicenter trial group. Diabetes-Care 16(1):8-15

Papendorp et al. 1995: Biochemical profile of osteoporotic patients on essential fatty acid supplementation. Nutr Res 15(3): 325-334.