Evening Primrose Oil

© Steven Foster

This fact sheet provides basic information about evening primrose oil—

common names, what the science says, potential side effects and 

cautions, and resources for more information.

Common Names—evening primrose oil, EPO

Latin Name—Oenothera biennis

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.

Evening primrose oil has been used since the 1930s as a folk or 

traditional remedy for eczema (a condition in which the skin becomes 

inflamed, itchy, or scaly because of allergies or other irritation). More 

recent folk uses include other conditions involving inflammation, such 

as rheumatoid arthritis; conditions affecting women’s health, such as 

breast pain associated with the menstrual cycle, menopausal 

symptoms, and premenstrual syndrome (PMS); cancer; and diabetes.

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 PMS, 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 all your health care providers about any complementary health practices you use. Give 

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

coordinated and safe care. For tips about talking with your health care providers about 

complementary and alternative medicine, see NCCAM’s Time to Talk campaign at 

nccam.nih.gov/timetotalk/. 

Sources

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

on June 11, 2009.

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

on June 11, 2009.

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.

For More Information

Visit the NCCAM Web site at nccam.nih.gov and view Using Dietary Supplements Wisely

(nccam.nih.gov/health/supplements/wiseuse.htm).

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

PubMed®

Web site: www.ncbi.nlm.nih.gov/sites/entrez

NIH Office of Dietary Supplements

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

NIH National Library of Medicine’s MedlinePlus

Evening Primrose Oil Listing: www.nlm.nih.gov/medlineplus/druginfo/natural/1006.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

D341

Created December 2006

Updated April 2012