Evening primrose oil (Oenothera biennis L.)
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| Evening
primrose oil |
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Evening primrose oil (EPO) contains an omega-6 essential fatty acid, gamma-linolenic
acid (GLA), which is believed to be the active ingredient. EPO has been
studied in a wide variety of disorders, particularly those affected by
metabolic products of essential fatty acids. However, high-quality evidence
for its use in most conditions is still lacking.
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Echte Nachtkerze, EPO, fever plant, gamma-linolenic acid (GLA), herbe aux anes,
Huile D'Onagre, kaempe natlys, king's cureall, la belle de nuit, nachtkerzenol,
night willow-herb, Oenothera communis Leveill, Oenothera
graveolens Gilib, omega-6 essential fatty acid, Onagra
biennis Scop, Onogra vulgaris , onagre bisannuelle,
scabish, Spach, stella di sera, sun drop, Teunisbloem.
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.
| Uses based on scientific evidence |
Grade* |
| Eczema (children and adults)
Several small studies of eczema suggest benefits of taking evening
primrose oil by mouth. Large well-designed studies are needed before a
strong recommendation can be made. Evening primrose oil is approved for
eczema in several countries outside of the United States.
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B |
| Skin irritation (atopic dermatitis in children and
adults)
Several small human studies of atopic dermatitis suggest benefits of
taking evening primrose oil by mouth. Large well-designed studies are
needed before a strong recommendation can be made. Evening primrose oil
is approved for atopic dermatitis in several countries outside of the
United States.
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B |
| Breast cancer
Not enough information is available to advise the use of evening
primrose oil for breast cancer. People with known or suspected breast
cancer should consult with a qualified healthcare professional about
possible treatments.
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C |
| Breast cysts
The limited available research does not demonstrate that evening
primrose oil has a significant effect on treating breast cysts.
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C |
| Breast pain (mastalgia)
Although primrose oil is used for breast pain in several European
countries, no high-quality human studies are currently available in this
area. Therefore, the available information does not allow recommendation
for or against the use of primrose oil in this condition.
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C |
| Chronic fatigue syndrome/post-viral infection
symptoms
Not enough information is available to advise the use of evening
primrose oil for symptoms of chronic fatigue syndrome or fatigue
following a viral infection.
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C |
| Diabetes
A small number of laboratory studies and theory suggests that evening
primrose oil may be helpful in diabetes, but more information is needed
before a recommendation can be made.
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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 before a recommendation can be made.
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C |
| Multiple sclerosis (MS)
It is theorized that primrose oil may be helpful in patients with MS
based on laboratory studies. Limited evidence is available in humans,
and a firm conclusion is not possible at this time.
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C |
| Obesity/weight loss
Initial human study suggests that evening primrose oil may have no
effects on weight loss.
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C |
| Pre-eclampsia/high blood pressure of pregnancy
Evening primrose oil is proposed to have effects on chemicals in the
blood called prostaglandins, which may play a role in pre-eclampsia.
However, more studies are needed before a firm conclusion can be drawn.
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C |
| Raynaud's phenomenon
Not enough scientific information is available to advise the use of
evening primrose oil for Raynaud's phenomenon.
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C |
| Rheumatoid arthritis
Benefits of evening primrose oil in the treatment of arthritis have not
clearly been shown. More information is needed before a recommendation
can be made.
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C |
| Scale-like dry skin (ichthyosis vulgaris)
Early studies do not show a benefit from evening primrose oil. However,
larger studies are needed to confirm this result.
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C |
| Asthma
Small studies do not show evening primrose oil to be useful in the
treatment of asthma. Further research is needed to confirm this
conclusion.
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D |
| Attention deficit hyperactivity disorder (ADHD)
Small human studies show no benefit from evening primrose oil in ADHD.
Further research is needed to confirm this conclusion.
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D |
| Cardiovascular health
Early study of evening primrose oil shows a lack of significant
beneficial effects on cardiovascular function and health.
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D |
| Menopause (flushing/bone metabolism)
Available studies do not show evening primrose oil to be helpful with
these potential complications of menopause.
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D |
| Pre-menstrual syndrome (PMS)
Small human studies do not report that evening primrose oil is helpful
for the symptoms of PMS. A large, well-designed study is needed before
any recommendation can be made.
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D |
| Psoriasis
Initial research does not show a benefit from evening primrose oil in
the treatment of psoriasis.
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D |
| Schizophrenia
Results from studies of mixed quality do not support the use of evening
primrose oil for schizophrenia.
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D |
*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;
F: Strong scientific evidence against this use.
Grading rationale
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.
Alcoholism, antioxidant, atherosclerosis, bronchitis, bruises (primrose oil
applied to the skin), chemotherapy-induced neuropathy (nerve damage), Crohn's
disease, cystic fibrosis, diabetes, disorders of the stomach and intestines,
fibroadenomas, hangover remedy, heart disease, hepatitis B, high cholesterol,
hot flashes, inflammation, irritable bowel syndrome, kidney stones, melanoma,
multiple sclerosis, pain, post-menopausal symptoms, post- natal depression,
preventing preterm delivery, promoting easier birth, Sjögren's syndrome, skin
conditions due to kidney failure in dialysis patients, systemic lupus
erythematosus (SLE), ulcerative colitis, weight loss, whooping cough, wound
healing (primrose oil poultice applied to the skin).
The below doses are based on scientific research,
publications, traditional use, or expert opinion. Many herbs and supplements
have not been thoroughly tested, and safety and effectiveness may not be proven.
Brands may be made differently, with variable ingredients, even within the same
brand. The below doses may not apply to all products. You should read product
labels, and discuss doses with a qualified healthcare provider before starting
therapy.
Adults (18 years and older)
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Studies in the treatment of eczema or atopic dermatitis have used doses of 4
to 8 grams of evening primrose oil (EPO) daily, taken by mouth, divided into
several smaller doses throughout the day. Studies of breast pain have used
doses of 3 grams EPO daily, taken by mouth, divided into several smaller doses
throughout the day.
Children (younger than 18 years)
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Studies in children treated for skin conditions have used 3 grams of evening
primrose oil daily, taken by mouth, divided into several smaller doses
throughout the day. It is reported that the maximum dose should not be greater
than 0.5 gram per kilogram of body weight daily. Medical supervision is
required.
The U.S. Food and Drug Administration does not strictly
regulate herbs and supplements. There is no guarantee of strength, purity or
safety of products, and effects may vary. You should always read product labels.
If you have a medical condition, or are taking other drugs, herbs, or
supplements, you should speak with a qualified healthcare provider before
starting a new therapy. Consult a healthcare provider immediately if you
experience side effects.
Allergies
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Allergy or hypersensitivity to evening primrose oil has not been widely
reported. Individuals with allergy or adverse reactions to plants in the
Onagraceae family, gamma-linolenic acid, or other ingredients in evening
primrose oil should avoid its use. Contact dermatitis (skin rash) is possible.
Side Effects and Warnings
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Several reports describe seizures in individuals taking evening primrose oil (EPO).
Some of these seizures developed in people with a previous seizure disorder,
or in individuals taking EPO in combination with anesthetics. Based on these
reports, people with seizure disorders should not take EPO. EPO should be used
cautiously with drugs used to treat mental illness such as chlorpromazine (Thorazine®),
thioridazine (Mellaril®), trifluoperazine (Stelazine®), or fluphenazine (Prolixin®),
due to an increased risk of seizure. Patients who plan to undergo surgery
requiring anesthesia should stop taking EPO two weeks ahead of time because of
the possibility of seizure.
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Other reports describe occasional headache, abdominal pain, nausea, and loose
stools in people taking EPO. In animal studies, gamma-linolenic acid (an
ingredient of evening primrose oil) is reported to decrease blood pressure.
Early results in human studies do not show consistent changes in blood
pressure.
Pregnancy and Breastfeeding
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There is not enough information to recommend the safe use of evening primrose
oil during pregnancy or breastfeeding.
Most herbs and supplements have not been thoroughly
tested for interactions with other herbs, supplements, drugs, or foods. The
interactions listed below are based on reports in scientific publications,
laboratory experiments, or traditional use. You should always read product
labels. If you have a medical condition, or are taking other drugs, herbs, or
supplements, you should speak with a qualified healthcare provider before
starting a new therapy.
Interactions with Drugs
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Because of reported seizures in people taking evening primrose oil alone or in
combination with certain medications used to treat mental illness, patients
should use caution when combining evening primrose oil with medications like
chlorpromazine (Thorazine®), thioridazine (Mellaril®), trifluoperazine (Stelazine®),
or fluphenazine (Prolixin®). Individuals undergoing surgery requiring general
anesthesia may be more sensitive to developing seizures, and should stop
taking evening primrose oil two weeks ahead of time. In people with a history
of seizures, doses of anti-seizure medications may require adjustment because
evening primrose oil may increase the risk of seizures.
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An ingredient of evening primrose oil, gamma-linolenic acid, is reported to
lower blood pressure in animal studies. Although human studies do not show
clear changes in blood pressure, people taking certain blood pressure
medications should consult with a healthcare professional before starting
evening primrose oil.
Interactions with Herbs and Dietary Supplements
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In animal studies, gamma-linolenic acid (an ingredient of evening primrose
oil) is reported to lower blood pressure. Therefore, in theory, evening
primrose oil may have effects on blood pressure, and should be used cautiously
when combined with other agents that may lower blood pressure.