Evening Primrose (Oenothera biennis)
Overview
Biennial herb growing to 8 in (20 cm). Has red blotches on stem, crinkled lanceshaped leaves, 4-petaled yellow flowers, and elongated seed capsules. The flowers, leaves, and stem bark of evening primrose have astringent and sedative properties. All three parts have been employed in the treatment of whooping cough. Evening primrose has also been taken for digestive problems and asthma, and used as a poultice to ease the discomfort of rheumatic disorders.
Safety & precautions
Do not take evening primrose oil if suffering from epilepsy.
Drug & food interactions
Evening primrose oil has been predicted to interact with antiplatelet and anticoagulant drugs, but data supporting this prediction are limited. Although seizures have occurred in a few schizophrenics taking phenothiazines and evening primrose oil, no adverse effects were seen in others, and there appears to be no firm evidence that evening primrose oil should be avoided by epileptic patients.
No interactions found.
Although seizures have occurred in a few schizophrenics taking phenothiazines and evening primrose oil, no adverse effects were seen in others, and there appears to be no firm evidence that evening primrose oil should be avoided by epileptic patients. Twenty-three patients were enrolled in a placebo-controlled study of evening primrose oil in schizophrenia. During the treatment phase, patients were given 8 capsules of Efamol in addition to their normal medication. Seizures developed in 3 patients, one during treatment with placebo. The other two patients were taking evening primrose oil: one was receiving fluphenazine decanoate 50 mg once every 2 weeks and the other fluphenazine decanoate 25 mg once every 2 weeks with thioridazine, which was later changed to chlorpromazine. 1 In another study, 3 long-stay hospitalised schizophrenics were taking evening primrose oil. Their schizophrenia became much worse and all 3 patients showed EEG evidence of temporal lobe epilepsy.2 In contrast, no seizures or epileptiform events were reported in a crossover study in 48 patients (most of them schizophrenics) taking phenothiazines when they were given evening primrose oil for 4 months.3 Concurrent use was also apparently uneventful in another study in schizophrenic patients.
The interaction between evening primrose oil and NSAIDs is based on a prediction only.
Evening primrose oil can inhibit platelet aggregation and increase bleeding time. It has therefore been suggested that it may have additive effects with other antiplatelet drugs, but evidence of this is generally lacking. In 12 patients with hyperlipidaemia given evening primrose oil 3 g daily for 4 months, platelet aggregation decreased and bleeding time increased by 40%. The evening primrose oil was given in the form of six 500-mg soft-gel capsules and the daily dose contained linoleic acid 2.2 g and gamolenic acid 240 mg.
No interactions found.
Habitat
Native to North America, evening primrose is now commonly found in many temperate zones around the world. It thrives in open areas, especially in dunes and sandy soil. Evening primrose is grown commercially for its seed oil.