Evidence

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.

Key to grades

A
Strong scientific evidence for this use
B
Good scientific evidence for this use
C
Unclear scientific evidence for this use
D
Fair scientific evidence against this use (it may not work)
F
Strong scientific evidence against this use (it likely does not work)

Grading rationale

Evidence gradeCondition to which grade level applies
B

Atopic dermatitis (eczema)

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.
C

Breast cancer

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.
C

Breast cysts

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.
C

Breast pain (mastalgia)

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.
C

Bronchitis

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.
C

Cardiovascular health

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.
C

Childbirth (labor induction/cervical ripening)

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.
C

Diabetes

EPO studies have demonstrated beneficial effects on serum markers in diabetes. Additional studies are required before a conclusion may be made.
C

Diabetic neuropathy (nerve damage)

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.
C

Dry eyes

Individuals with dry eyes had improved symptoms after supplementation with GLA, a component of EPO. Additional research is needed in this area.
C

Dyslexia (difficulty reading)

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.
C

High cholesterol

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.
C

Inflammatory bowel disease (Crohn's disease, ulcerative colitis)

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.
C

Liver cancer

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.
C

Liver disease

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.
C

Multiple sclerosis (MS)

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.
C

Obesity/weight loss

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.
C

Osteoporosis

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.
C

Postviral/chronic fatigue syndrome

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.
C

Pre-eclampsia/high blood pressure of pregnancy

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.
C

Raynaud's phenomenon (poor circulation)

There have been reports of EPO improving symptoms of Raynaud's phenomenon. Well-designed human studies are needed before a conclusion can be made.
C

Rheumatoid arthritis

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.
C

Sinus disorders

An herbal combination product containing primrose has been used in people with sinus inflammation. Additional high quality research in this area is needed.
C

Scale-like dry skin (ichthyosis vulgaris)

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.
C

Skin conditions (cellulite)

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.
D

Alcohol intoxication

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.
D

Asthma

Research has demonstrated a lack of efficacy for evening primrose oil (EPO) in people with asthma. Further research is needed to confirm this conclusion.
D

Attention deficit hyperactivity disorder (ADHD)

Several studies show a lack of benefit from evening primrose oil in treating ADHD. Further research is needed to confirm this conclusion.
D

Hepatitis B

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.
D

Infant development / neonatal care

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.
D

Menopause (flushing/bone metabolism)

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.
D

Pre-menstrual syndrome (PMS)

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.
D

Psoriasis (skin disorder)

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.
D

Schizophrenia

Results from most studies do not support EPO use for schizophrenia. Additional well-designed clinical trials are needed.

Uses based on tradition or theory

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Acne, acute respiratory distress syndrome (lung condition), anti-aging, antioxidant, bladder disturbances, blood clot prevention, bruises (topical), cancer, cancer prevention, chemical sensitivities (multiple), chemotherapy induced nausea and vomiting, chemotherapy-induced neuropathy (nerve damage), clogged arteries, common cold treatment (symptomatic relief), cystic fibrosis, depression, dry skin, fertility, gastritis (stomach inflammation), gastrointestinal disorders, hangover remedy, headache, hemorrhoids, high blood pressure, inflammation, itching, kidney disease, lupus, mental illness, migraine, pain, postpartum depression, osteoarthritis, scleroderma (skin hardening), Sjogren's syndrome (dry eyes and mouth), skin cancer, skin conditions (in dialysis patients), stomach ulcer, tumors (noncancerous breast tumors/fibroadenomas), urolithiasis (urinary tract stones), vision (acuity), whooping cough, wound healing (poultice).

This evidence-based monograph was prepared by The Natural Standard Research Collaboration

www.naturalstandard.com