An infusion of the whole plant is thought to have a sedative and astringent properties, and has traditionally been used for asthmatic coughs, gastrointestinal disorders, whooping cough, and as a sedative painkiller. Poultices were reputed to ease bruises and to speed wound-healing.
Evening Primrose oil has been used for premenstrual syndrome, psoriasis, multiple sclerosis, hypercholesterolaemia, rheumatoid arthritis, Reynaurd's phenomenon, Sjorgren's syndrom, post-viral fatigue syndrome, asthma, and diabetic neuropathy.
The seed oil of evening primrose contains the EFAs linoleic acid and gamma-linolenic acid (GLA). Both are prostaglandin precursors. GLA is though to increase the ratio of non-inflammatory compounds.
GLA and its metabolite dihomogamma-linolenic acid (DGLA) are precursors of both of the inflammatory prostaglandins E2 (PGE2) series via arachadonic acid (AA), and the less inflammatory prostaglandin E1 (PGE1) series.
PGE1 acts as an anti-inflammatory, immunoregulatory, vasodilator, inhibits platelet aggregation and cholesterol bio-synthesis, promotes hypo-tension, and elevates cyclic AMP (inhibits phospholipase A2).