Evening primrose oil (Oenothera biennis L.)
Evening primrose oil (Oenothera biennis L.)
Natural Standard Bottom Line Monograph, Copyright © 2013 (www.naturalstandard.com). Commercial distribution prohibited. This monograph is intended for informational purposes only, and should not be interpreted as specific medical advice. You should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.
While some complementary and alternative techniques have been studied scientifically, high-quality data regarding safety, effectiveness, and mechanism of action are limited or controversial for most therapies. Whenever possible, it is recommended that practitioners be licensed by a recognized professional organization that adheres to clearly published standards. In addition, before starting a new technique or engaging a practitioner, it is recommended that patients speak with their primary healthcare provider(s). Potential benefits, risks (including financial costs), and alternatives should be carefully considered. The below monograph is designed to provide historical background and an overview of clinically-oriented research, and neither advocates for or against the use of a particular therapy.
Related Terms
Bronchipret TP FCT, Echte Nachtkerze, EPO, fever plant, gamma-linolenic acid, herbe aux anes, Huile D'Onagre, kaempe natlys, king's cureall, la belle de nuit, linoleic acid, nachtkerzenol, night willow-herb, Oenothera communis Leveill, Oenothera graveolens Gilib, omega-6 essential fatty acid, Onagra biennis Scop, Onogra vulgaris, onagre bisannuelle, primrose, primrose oil, scabish, Spach, stella di sera, sun drop, Teunisbloem.
Background
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.
Scientific Evidence
Uses 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. |
Grade* |
Atopic dermatitis (eczema) There are several studies of evening primrose oil taken by mouth for eczema. Large well-designed studies are needed before a strong recommendation can be made. Evening primrose oil is approved for skin disorders in several countries outside of the United States. |
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. |
C |
Breast cysts The limited available research does not demonstrate that evening primrose oil has a significant effect on treating breast cysts. |
C |
Breast pain (mastalgia) Although primrose oil is used for breast pain in several European countries, high-quality human studies using this treatment are lacking. Therefore, the available information does not allow recommendation for or against the use of primrose oil in this condition. |
C |
Bronchitis There is evidence that primrose oil, in combination with thyme, may have some benefits in the treatment of acute bronchitis. However, it is unclear if primrose alone is useful in treating bronchitis. More studies are needed to examine the effectiveness of primrose oil alone as a therapy for bronchitis. |
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. |
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 firm recommendation can 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 before a strong recommendation can be made. |
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. |
C |
Obesity/weight loss Initial human study is unclear about the effects that evening primrose oil may have on weight loss. |
C |
Osteoporosis Primrose oil has been suggested as a possible treatment for bone loss/osteoporosis. However, osteoporosis studies using primrose oil as a treatment are lacking. Well-designed human trials are needed before primrose oil can be recommended for osteoporosis therapy. |
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. |
C |
Raynaud's phenomenon Not enough scientific information is available to advise the use of evening primrose oil for Raynaud's phenomenon. |
C |
Rheumatoid arthritis Benefits of evening primrose oil in the treatment of arthritis have not clearly been shown. More information is needed before a firm recommendation can be made. |
C |
Scale-like dry skin (ichthyosis vulgaris) Not enough scientific information is available to advise the use of evening primrose oil for dry skin. |
C |
Asthma Available evidence does not support the use of evening primrose oil as a treatment for asthma. Further research is needed to confirm this conclusion. |
D |
Attention deficit hyperactivity disorder (ADHD) Small human studies show a lack of benefit from evening primrose oil in ADHD. Further research is needed to confirm this conclusion. |
D |
Cardiovascular health Early study of evening primrose oil shows a lack of beneficial effects on cardiovascular function and health. |
D |
Menopause (flushing/bone metabolism) Available studies do not show evening primrose oil to be helpful with these potential complications of menopause. More evidence of effectiveness is needed before primrose can be recommended as a treatment for menopausal symptoms. |
D |
Pre-menstrual syndrome (PMS) Small human studies do not report that evening primrose oil is helpful for the symptoms of PMS. |
D |
Psoriasis Initial research does not show a benefit from evening primrose oil in the treatment of psoriasis. |
D |
Schizophrenia Results from studies of mixed quality do not support the use of evening primrose oil for schizophrenia. In contrast, fish oils have shown some promise in this disease, and further study is merited. |
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 (it may not work); F: Strong scientific evidence against this use (it likely does not work). |
|
Tradition/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 health care professional.
Alcoholism, antioxidant, atherosclerosis, bruises (primrose oil applied to the skin), cancer, cancer prevention, chemotherapy-induced neuropathy (nerve damage), Crohn's disease, cystic fibrosis, disorders of the stomach and intestines, hangover remedy, heart disease, hemorrhoids, hepatitis B, high cholesterol, inflammation, irritable bowel syndrome, kidney stones, labor and delivery (preventing preterm delivery and promoting easier birth), melanoma, multiple sclerosis, pain, post-natal depression, scleroderma, Sjögren's syndrome, skin conditions due to kidney failure in dialysis patients, stomach pain, systemic lupus erythematosus (SLE), tumors (fibroadenomas), ulcerative colitis, whooping cough, wound healing (primrose oil poultice applied to the skin).
Dosing
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)
Studies in the treatment of eczema 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 treating 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)
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.
Safety
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
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
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.
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
There is not enough information to recommend the safe use of evening primrose oil during pregnancy or breastfeeding.
Interactions
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
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.
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.
Possible additive effects may occur when primrose oil is taken with anticoagulants (blood thinners) and drugs used to treat arthritis.
Possible interactions may occur with antidepressants, including monoamine oxidase inhibitors (MAOIs) and selective serotonin reuptake inhibitors (SSRIs). Interactions may also occur with the following: antineoplastic agents, anti-obesity agents, antiviral agents, CNS stimulants, drugs metabolized by the liver, gastrointestinal treatments, and neurological agents.
Interactions with Herbs and Dietary Supplements
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.
Theoretically, evening primrose oil may have additive effects when taken concomitantly with thyme, because a fixed combination of thyme fluid extract and primrose root tincture (Bronchicum Tropfen) has been used in studies to treat bronchitis.
Primrose oil may potentially interact with herbs and supplements used to treat arthritis, gastrointestinal disorders, obesity, seizures, viral infections, and psychosis. Primrose oil may interact with stimulants and herbs and supplements that are metabolized in the liver. Antineoplastics may also interact with primrose.
Author Information
This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).
References
Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.
Blommers J, de Lange-De Klerk ES, Kuik DJ, et al. Evening primrose oil and fish oil for severe chronic mastalgia: a randomized, double-blind, controlled trial. Am J Obstet Gynecol 2002;187(5):1389-1394. View Abstract
Cancelo Hidalgo MJ, Castelo-Branco C, et al. Effect of a compound containing isoflavones, primrose oil and vitamin E in two different doses on climacteric symptoms. J Obstet Gynaecol 2006 May;26(4):344-7. View Abstract
Gateley CA, Pye JK, Harrison BJ et al. Evening primrose oil (Efamol), a safe treatment option for breast disease. Breast Cancer Res Treat 2001;(14):161.
Gruenwald J, Graubaum HJ, Busch R. Evaluation of the non-inferiority of a fixed combination of thyme fluid- and primrose root extract in comparison to a fixed combination of thyme fluid extract and primrose root tincture in patients with acute bronchitis. A single-blind, randomized, bi-centric clinical trial. Arzneimittelforschung 2006;56(8):574-81. View Abstract
Hederos CA, Berg A. Epogam evening primrose oil treatment in atopic dermatitis and asthma. Arch Dis Child 1996; 75(6):494-497. View Abstract
Humphreys F, Symons J, Brown H, et al. The effects of gamolenic acid on adult atopic eczema and premenstrual exacerbation of eczema. Eur J Dermatol 1994;4(598):603.
Huntley AL, Ernst E. A systematic review of herbal medicinal products for the treatment of menopausal symptoms. Menopause 2003;10(5):465-476. View Abstract
Jack AM, Keegan A, Cotter MA, et al. Effects of diabetes and evening primrose oil treatment on responses of aorta, corpus cavernosum and mesenteric vasculature in rats. Life Sci 2002;71(16):1863-1877. View Abstract
Joe LA, Hart LL. Evening primrose oil in rheumatoid arthritis. Ann Pharmacother 1993;27(12):1475-1477. View Abstract
Joy CB, Mumby-Croft R, Joy LA. Polyunsaturated fatty acid supplementation for schizophrenia. Cochrane Database Syst Rev. 2003;(2):CD001257. View Abstract
Kemmerich B. Evaluation of efficacy and tolerability of a fixed combination of dry extracts of thyme herb and primrose root in adults suffering from acute bronchitis with productive cough. A prospective, double-blind, placebo-controlled multicentre clinical trial. Arzneimittelforschung 2007;57(9):607-15. View Abstract
Puri BK. The safety of evening primrose oil in epilepsy. Prostaglandins Leukot Essent Fatty Acids 2007 Aug;77(2):101-3. View Abstract
Qureshi S, Sultan N. Topical nonsteroidal anti-inflammatory drugs versus oil of evening primrose in the treatment of mastalgia. Surgeon 2005 Feb;3(1):7-10. View Abstract
Whitaker DK, Cilliers J, de Beer C. Evening primrose oil (Epogam) in the treatment of chronic hand dermatitis: disappointing therapeutic results. Dermatology 1996;193(2):115-120. View Abstract
Yoshimoto-Furuie K, Yoshimoto K, Tanaka T, et al. Effects of oral supplementation with evening primrose oil for six weeks on plasma essential fatty acids and uremic skin symptoms in hemodialysis patients. Nephron 1999;81(2):151-159. View Abstract
Copyright © 2013 Natural Standard (www.naturalstandard.com)
The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.
Updated:
March 22, 2017