Evening primrose oil (Oenothera biennis L.)


Native Americans traditionally considered the evening primrose plant's seeds, leaves, and roots to be a food. They also used the plant to treat bruises or wounds, hemorrhoids, stomach problems, and sore throats.
Oil extracted from evening primrose (Oenothera biennis) plant seeds consists of a high amount of unsaturated fatty acids. These fatty acids include omega-6 fatty acids, linolenic acid, and gamma-linolenic acid (GLA). GLA has been licensed for treating breast pain and eczema in numerous countries.
Evening primrose oil (EPO) has been studied for several disorders, particularly those affected by metabolic products of essential fatty acids. There is good scientific evidence to support EPO for eczema treatment.

Related Terms

(+)-catechin, aceite de onagra (Spanish), arachadonic acid (AA), cis-linoleic acid, dihomo-gamma-linolenic acid (DGLA), Echte Nachtkerze (German), ellagic acid, EPO, fever plant, gallic acid, gamma-linolenic acid (GLA), gamolenic acid (GLA), herbe aux anes (French), Huile D'Onagre (French), kaempe natlys, King's Cureall, la belle de nuit (French), linoleic acid (LA), nachtkerzenol (German), night willow-herb, Oenothera biennis L., Oenothera communis Leveill, Oenothera graveolens Gilib, Oenothera paradoxa, omega-6 essential fatty acid, Onagra biennis Scop, Onagraceae (family), Onogra vulgaris, onagre bisannuelle, pentagalloylglucose, penta-O-galloyl-beta-D-glucose, primrose oil, procyanidins, scabish, Spach, stella di sera, sun drop, Teunisbloem (Dutch), unsaturated fatty acids.
According to secondary sources, Epogam (40mg GLA and 10mg vitamin E) and Efamast (gamolenic acid) had their product licenses withdrawn October 7, 2002, following a review by the MCA/Committee on Safety of Medicines (CSM) of all the relevant information. It was determined that the information available did not support the standard of efficacy required for the authorization of these products as medicines for the treatment of eczema and mastalgia.
Combination product examples: Bronchicum® Tropfen (thyme and primrose), Bronchipret® TP FCT (thyme and primrose), Bronchicum® Elixir S (thyme and primrose).
Zestra® (borage seed oil, evening primrose oil, angelica root extract, and coleus extract)
The combination compound was called IOVE and was composed of 60mg isoflavones, 440mg primrose oil (consisting of 9-10% gamma linolenic acid (GLA)), and 10mg vitamin E.

evidence table

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.
Atopic dermatitis (eczema) (Grade: B)
Overall, evidence suggests a moderate improvement of eczema with EPO. Large, well-designed studies are needed to provide a definitive conclusion. EPO has been approved for atopic dermatitis and eczema in several countries outside the United States.
Breast cancer (Grade: C)
Early research suggests a beneficial effect of evening primrose oil (EPO) over corn oil in breast tumors. In human research, EPO treatment helped prevent breast cancer recurrence. However, additional studies using EPO alone are needed in this area.
Breast cysts (Grade: C)
Human research is lacking for beneficial effects in EPO use for breast cysts. More well-designed studies are needed before a conclusion may be made.
Breast pain (mastalgia) (Grade: C)
Evening primrose oil (EPO) is licensed for the treatment of mastalgia (breast pain) in the United Kingdom. Conflicting evidence has been reported with EPO in the treatment of breast pain. Additional well-designed studies are needed before a firm conclusion may be made.
Bronchitis (Grade: C)
It is unclear if evening primrose oil (EPO) is an effective treatment for bronchitis. Several studies have evaluated EPO in combination with thyme with some evidence of benefit. Additional well-designed studies using EPO alone are needed.
Cardiovascular health (Grade: C)
Research with EPO has shown a lack of significant beneficial effects on heart function and health. Early research suggests that EPO may decrease blood pressure. Additional research is needed in this area.
Childbirth (labor induction/cervical ripening) (Grade: C)
Historically, EPO has been used to promote easier birth, prevent preterm delivery, induce labor, and ripen the cervix. Low quality studies have revealed that evidence of benefit is lacking. Additional well-designed studies are needed on this topic.
Diabetes (Grade: C)
EPO studies have demonstrated beneficial effects on serum markers in diabetes. Additional studies are required before a conclusion may be made.
Diabetic neuropathy (nerve damage) (Grade: C)
Gamma-linolenic acid (GLA), one of the components of evening primrose oil, may be helpful in people with diabetic neuropathy. Additional studies are needed in this area.
Dry eyes (Grade: C)
Individuals with dry eyes had improved symptoms after supplementation with GLA, a component of EPO. Additional research is needed in this area.
Dyslexia (difficulty reading) (Grade: C)
EPO may benefit people with dyslexia by improving movement skills. However, many studies conducted were low quality or EPO was part of a combination product. Further high quality research evaluating EPO alone is needed.
High cholesterol (Grade: C)
Human research has shown EPO may lower cholesterol and triglycerides. However, there are conflicting reports. Additional studied are needed before a conclusion may be made.
Inflammatory bowel disease (Crohn's disease, ulcerative colitis) (Grade: C)
Evening primrose oil has been studied in people with ulcerative colitis with evidence of benefit. The effects of EPO alone are unclear. Additional research is warranted in this area.
Liver cancer (Grade: C)
Clinical trials have been conducted to assess the effects of EPO on liver cancer with mixed results. Additional studies are required before a conclusion may be made.
Liver disease (Grade: C)
Some research has shown that evening primrose lacks benefit in liver disease symptoms. Other studies suggest that EPO may reduce itching in people with liver disease. Additional, well-designed studies are necessary before a conclusion may be made.
Multiple sclerosis (MS) (Grade: C)
Investigation of linoleic acid (LA) and gamma-linolenic acid (GLA) in the management of MS began in the 1970s. However, evidence is limited regarding EPO for multiple sclerosis. Additional research is needed in this area.
Obesity/weight loss (Grade: C)
Research suggests a lack of evidence for EPO's efficacy in weight-loss and obesity. Additional studies are needed before a conclusion may be made.
Osteoporosis (Grade: C)
Although primrose oil has been suggested as a possible treatment for bone loss and osteoporosis, there is a lack of research involving primrose oil alone. Well-designed research is needed before a firm conclusion may be made.
Postviral/chronic fatigue syndrome (Grade: C)
Studies with high doses of evening primrose oil shoed evidence of benefit in people with chronic fatigue syndrome. However, additional well-designed studies are needed before a conclusion may be made.
Pre-eclampsia/high blood pressure of pregnancy (Grade: C)
Evening primrose oil may have effects on chemicals in the blood called prostaglandins, which may play a role in pre-eclampsia. The combination of EPO and fish oil may be equally as effective as magnesium oxide for pre-eclampsia. Further research in this area is needed.
Raynaud's phenomenon (poor circulation) (Grade: C)
There have been reports of EPO improving symptoms of Raynaud's phenomenon. Well-designed human studies are needed before a conclusion can be made.
Rheumatoid arthritis (Grade: C)
Evening primrose oil for arthritis treatment has conflicting results. GLA may benefit arthritis better than corn oil. More research is needed before a firm conclusion can be made.
Sinus disorders (Grade: C)
An herbal combination product containing primrose has been used in people with sinus inflammation. Additional high quality research in this area is needed.
Scale-like dry skin (ichthyosis vulgaris) (Grade: C)
Early research with evening primrose oil reports a lack of benefit for treating scale-like dry skin. However, additional studies are needed to confirm this conclusion.
Skin conditions (cellulite) (Grade: C)
A combination product containing EPO has had conflicting results for cellulite reduction. Well-designed studies on EPO alone are needed before conclusions can be drawn.
Alcohol intoxication (Grade: D)
Studies have described the effects of individuals receiving EPO after consuming alcohol and in people with alcoholism. However, well-designed studies evaluating EPO alone are lacking. Additional research is warranted before a conclusion may be made.
Asthma (Grade: D)
Research has demonstrated a lack of efficacy for evening primrose oil (EPO) in people with asthma. Further research is needed to confirm this conclusion.
Attention deficit hyperactivity disorder (ADHD) (Grade: D)
Several studies show a lack of benefit from evening primrose oil in treating ADHD. Further research is needed to confirm this conclusion.
Hepatitis B (Grade: D)
In human research, evidence of benefit following GLA (a component of EPO) supplementation was lacking in individuals with hepatitis B. Additional study is needed in this area.
Infant development / neonatal care (Grade: D)
In infants, various effects on fatty acid levels have been described with EPO and fish oil. However, well designed research evaluating EPO alone is still warranted.
Menopause (flushing/bone metabolism) (Grade: D)
Some research reports a lack of evidence that EPO is useful for menopause symptoms, such as flushing and bone mineral density. A combination EPO essential oil and massage may reduce blood pressure. Additional study is needed in this area.
Pre-menstrual syndrome (PMS) (Grade: D)
EPO is widely used internationally by women for symptoms of premenstrual syndrome (PMS) and premenstrual dysphoric disorder (PMDD). According to some experts, EPO is regarded as an effective treatment for PMS symptoms. However, evidence is conflicting with studies showing a lack of benefit. Additional research is needed in this area.
Psoriasis (skin disorder) (Grade: D)
Initial research lacks a benefit from EPO for psoriasis treatment. Some studies have been done in combination with fish oil, and the effects of EPO alone are unclear. More well-designed trials are needed before a conclusion can be drawn.
Schizophrenia (Grade: D)
Results from most studies do not support EPO use for schizophrenia. Additional well-designed clinical trials are needed.