Evening Primrose
Oenothera officinalis

Location
Wildflower plot.

Description
Native to Europe and North America, this hardy biennial herb is now cultivated in other temperate regions. Evening primrose grows well in all zones and produces yellow flowers that open at twilight (Newcomb 1977). Each bloom lasts only one night.

History
Evening primrose was used in American folk medicine as an astringent and was a remedy for wounds, bruises, and skin eruptions. Eastern Native Americans used a poultice of the whole plant for bruises, and a decoction of the root for hemorrhoids (Foster 2006). Evening primrose was also used as a sedative, to treat gastrointestinal disorders, and to calm asthma and whooping cough (Grieve 1931).

Current medicinal uses
Modern herbalists use the herb and the oil from its seeds, which is a source of GLA (gamma-linolenic acid), to treat eczema and other skin conditions (Foster 2006). Research suggests that evening primrose oil (EPO) may help prevent and treat diabetic neuropathy, as the oil is high in GLA and linoleic acid, which are both important components of nerve cell membranes (Halat and Dennehy 2003). A 2003 study on the effects of polyunsaturated fatty acids (PUFAs) found that EPO did not significantly improve vascular tone, although PUFAs in fish oil showed promise in benefiting microvascular function (Khan 2003).

EPO may be an effective treatment for patients suffering from atopic dermatitis. A recent study of 53 patients found EPO significantly better than placebo in reducing the severity of atopic dermatitis (Senapati 2008). A previous meta-analysis of 26 randomized placebo-controlled trials including 1207 patients with atopic eczema concluded that EPO has a beneficial effect on symptoms such as redness and inflammation between 4 and 8 weeks after treatment is initiated. However, this effect is less pronounced with concurrent use of potent steroids (Morse 2006).

EPO is approved for treatment of mastalgia (breast pain) in the United Kingdom, but research indicates that topical application of nonsteroidal anti-inflammatories is more effective in treating breast pain (Qureshi 2005). An earlier study of EPO showed it to be no more effective than wheat germ oil or corn oil in treating mastalgia (Blommers 2002). Research into EPO’s value in treating rheumatoid arthritis, premenstrual syndrome, breast cysts, hot flashes, hepatitis B, and psoriasis has not yielded convincing results demonstrating benefit over placebo (Fugh-Berman 2003).

Adverse effects
None known.

References
Blommers J et al. Evening primrose oil and fish oil for severe chronic mastalgia: a randomized, double-blind, controlled trial. Am J Obstet Gynecol. 2002; 187(5): 1389-94.

Fugh-Berman A. The 5-Minute Herb and Dietary Supplement Consult. Lippincott, Williams, and Wilkins, Baltimore, 2003: 122-123.

Grieve M. A Modern Herbal. Tiger Books International, London, 1998 (first published in 1931 by Jonathan Cape Ltd).

Halat KM, Dennehy CE. Botanicals and dietary supplements in diabetic peripheral neuropathy. J of the American Board of Family Practice. 2003; 16(1):47-57.

Khan F et al. The effects of dietary fatty acid supplementation on endothelial function and vascular tone in healthy subjects. Cardiovasc Res. 2003; 59(4): 955-62.

Morse NL, Clough PM. A meta-analysis of randomized, placebo-controlled clinical trials of Efamol evening primrose oil in atopic eczema. Where do we go from here in light of more recent discoveries? Curr Pharm Biotechnol. 2006; 7(6): 503-24. http://www.ncbi.nlm.nih.gov/pubmed/17168667?ordinalpos=10&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum

Newcomb L. Newcomb’s Wildflower Guide. Little, Brown and Company, Boston, 1977.

Senapati S. Evening primrose oil is effective in atopic dermatitis: a randomized placebo-controlled trial. Indian J Dermatol Venereol Leprol. 2008; 74(5): 447-52.

Qureshi S, Sultan N. Topical nonsteroidal anti-inflammatory drugs versus oil of evening primrose in the treatment of mastalgia. Surgeon. 2005; 3(1): 7-10. (Abstract only)