Evening Primrose

Evening primrose oil (EPO) is obtained from the seed of the plant species Oenothera biennis.

EPO is also known as fever plant, huile d’onagre, king’s cureall, night willow-herb, scabish, suncups, and sundrops.

EPO may be used as a food supplement for the essential fatty acids, linoleic acid (LA), and γ-linolenic acid (GLA).

Infusion of the whole plant has been used for asthma, GI disorders, whooping cough, and as a sedative pain killer.

Other evidence indicates that orally administered primrose oil does not relieve symptoms of premenstrual syndrome and does not have any effect in shortening the length of pregnancy and labor.

EPO had been licensed in Britain for treatment of atopic eczema and cyclic and noncyclic mastalgia. Cochrane meta-analysis found that evening primrose oil capsules were ineffective for eczema.

Other potential uses for EPO include PMS, psoriasis, MS, hypercholesterolemia, rheumatoid arthritis, Raynaud phenomenon, Sjögren’s syndrome, postviral fatigue syndrome, asthma, and diabetic neuropathy. Without solid evidence it is effective, but with recurrent anecdotal evidence of beneficial outcomes.

Speculation that EPO may increase risk of temporal lobe epilepsy or reduce the seizure threshold in schizophrenic pts taking epileptogenic drugs (e.g., phenothiazines).

EPO may cause a decrease in blood clotting.

Obstetrics: Oral EPO administration during pregnancy may have an association with a protracted phase of labor, prolonged rupture of membranes, oxytocin augmentation, vacuum extraction, and arrest of descent. One case report exists of transient petechiae and ecchymosis in a newborn after 6.5 g of oral EPO intake by the mother the week before birth.