Evening Primrose Oil 

This fact sheet provides basic information about evening primrose oil—common 

names, uses, potential side effects, and resources for more information. Evening 

primrose is a plant native to North America, but it grows in Europe and parts of 

the Southern Hemisphere as well. It has yellow flowers that bloom in the 

evening. Evening primrose oil contains gamma-linolenic acid (GLA), an essential 

fatty acid. Essential fatty acids are required by the body for growth and 

development, and must be obtained from the diet. 

Common Names—evening primrose oil, EPO 

Latin Name—Oenothera biennis 

What It Is Used For 

•	 Evening primrose oil has been used since the 1930s for eczema (a condition 

in which the skin becomes inflamed, itchy, or scaly because of allergies or 

other irritation). 

•	 More recently it has been used for other conditions involving inflammation, 

such as rheumatoid arthritis. 

•	 Evening primrose oil is used for conditions affecting women’s health, such 

as breast pain associated with the menstrual cycle, menopausal symptoms, 

and premenstrual syndrome. 

•	 Other conditions for which evening primrose oil is used include cancer 

and diabetes. 

How It Is Used 

Evening primrose oil is extracted from the seeds of the evening primrose. The 

oil is usually put into capsules for use. 

What the Science Says 

•	 Evening primrose oil may have modest benefits for eczema, and it may be 

useful for rheumatoid arthritis and breast pain. However, study results are 

mixed, and most studies have been small and not well designed. 

•	 Evening primrose oil does not appear to affect menopausal symptoms. 

•	 Although some clinical trials have shown a benefit of evening primrose oil 

for premenstrual syndrome, the best-designed trials found no effect. 

•	 There is not enough evidence to support the use of evening primrose oil for 

other health conditions. 
 

 

 

 

Side Effects and Cautions 

•	 Evening primrose oil is well tolerated by most people. Mild side effects include 

gastrointestinal upset and headache. 

•	 Tell your health care providers about any complementary and alternative practices you 

use. Give them a full picture of what you do to manage your health. This will help ensure 

coordinated and safe care. 

Sources 

Shahidi F, Miraliakbari H. Evening primrose (Oenothera biennis). In: Coates P, Blackman M, Cragg G, et al., eds. 

Encyclopedia of Dietary Supplements. New York, NY: Marcel Dekker; 2005:197-210. 

Evening primrose oil. Natural Medicines Comprehensive Database Web site. Accessed at 

http://www.naturaldatabase.com on July 6, 2007. 

Evening primrose oil (Oenothera biennis L.). Natural Standard Web site. Accessed at http://www.naturalstandard.com

on July 3, 2007. 

For More Information 

Visit the NCCAM Web site at nccam.nih.gov and view: 

•	 What’s in the Bottle? An Introduction to Dietary Supplements at nccam.nih.gov/health/bottle/

•	 Herbal Supplements: Consider Safety, Too at nccam.nih.gov/health/supplement-safety/

NCCAM Clearinghouse 

Toll-free in the U.S.: 1-888-644-6226 

TTY (for deaf and hard-of-hearing callers): 1-866-464-3615 

E-mail: info@nccam.nih.gov

CAM on PubMed 

Web site: nccam.nih.gov/camonpubmed/ 

NIH Office of Dietary Supplements 

Web site: www.ods.od.nih.gov

NIH National Library of Medicine’s MedlinePlus 

Evening Primrose Listing: www.nlm.nih.gov/medlineplus/druginfo/natural/patient-primrose.html 

This publication is not copyrighted and is in the public domain. Duplication is encouraged. 

NCCAM has provided this material for your information. It is not intended to substitute for 

the medical expertise and advice of your primary health care provider. We encourage you to 

discuss any decisions about treatment or care with your health care provider. The mention of 

any product, service, or therapy is not an endorsement by NCCAM. 

National Institutes of Health 

♦♦♦

U.S. Department of Health and Human Services 

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Created December 2006 

Updated March 2008 

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