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Is Evening Primrose Oil an Effective Treatment of Mastalgia?

A Literary Review





Cassandra Brooks

September 18, 2006

Health Psychology




What is Evening Primrose?


Evening primrose is an herb that comes in many different forms, all of which are classified under the genus Onagraceae.  Specifically in North America there are three prevalent forms under the scientific names: Oenothera biennis, Oenothera caespitosa and Oenothera hookeri.  One might be more familiar with the common names for evening primrose such as King’s Cure-all, night willow herb, coffee plant, fever plant and German ranpion. (Passwater, 1981).  Evening primrose is a versatile plant and can be found near streams, mountains, roadside, and in the middle of the desert.  The variation in habitat explains the various common names for the herb.  In the book What Herbs Are All About by Jack Challem, evening primrose is described as a “delicately petaled, large-flowered plant with a light green vein running down the centers of the lance-shaped leaves.  The plant is generally between two to five feet tall.” It is referred to as evening primrose because the flowers bloom in the evening and last for about an hour before they wither to a pinkish hue. The evening primrose plant takes two years to bloom and ceases to produce flowers in the fall.




Who Discovered the Supposed Medicinal Purposes for Evening Primrose?


It is believed that the Indians taught the pilgrims about the medicinal benefits of evening primrose and then it was quickly exported to England.  It was in England that the name “King’s Cure-all” was adopted.   Externally, evening primrose was used to heal wounds and calm skin that was inflamed.  Internally, the Indians used the root of the plant to calm whooping cough, asthmatic cough and tuberculosis cough.  In addition, it was used as an astringent, a pain killer, sedative and diuretic (






What Are the Medicinal Purposes of Evening Primrose Oil?


Evening primrose oil is believed to aid in the treatment of many illnesses.  In some sense it can be considered a “cure-all” drug.  Its supposed treatments include, mastalgia (breast pain), diabetes, obesity/weight loss, pre-eclampsia, diabetic neuropathy, chronic fatigue syndrome, raynaud’s phenomenon, dry skin, rheumatoid arthritis, asthma, attention deficit disorder, pre-menstrual syndrome (PMS), menopause, cardiovascular health, psoriasis, schizophrenia, breast cysts, breast cancer, and multiple sclerosis (MS) (  With such an exhaustive list one would think of evening primrose oil as a miracle drug; however for some claims there is not much scientific evidence to back them up.  So, the intent of this paper is to do a literature review of the scientific evidence for the treatment of mastalgia.  Mastalgia is commonly referred to as breast pain and will be explained in greater detail a little later.



What is the specific component in evening primrose oil that gives it its medicinal value?


Evening primrose oil contains gamma linolenic acid (GLA).  The body converts gamma linolenic acid into a hormone-like substance called prostaglandin.  Prostaglandins help in the reduction of inflamed cells specifically Prostaglandin E1 (PGE1).  Linolenic acid in general is a dietary supplement of polyunsaturated fatty acids (PUFA).  Linolenic acid is also found in sunflower seeds and safflower oils.  The proposed difference between gamma linolenic acid and linolenic acid is that the transition of linolenic acid to prostaglandins can be inhibited by many things such as the aging process, saturated fat, and hydrogenated vegetables oils.  Therefore, the premise behind evening primrose oil is that since it is more concentrated with gamma linolenic acid, it is more effective than the intake of linolenic acid from commonly found nuts and seeds. 


The following is the chemical diagram of Gamma Linolenic Acid




Is Evening Primrose Oil Safe?


Some side effects of evening primrose oil include nausea, diarrhea, soft stools, burping, stomach bloating, and intestinal gas.  In addition, individuals who are taking any form of aspirin or blood thinning medication should avoid excessive use of evening primrose oil seeing as it can increase bleeding and bruising.  Finally, anyone “taking a class of psychiatric drugs called phenothiazines, such as chlorpromazine or prochlorperazine” should avoid evening primrose oil because the combination can lead to seizures (



What is Mastalgia?


Mastalgia is commonly called breast pain.  There are two main forms: cyclical and non-cyclical.  Non-cyclical mastalgia could be pain that is felt in the breast but actually originates from a different area of the body such as nearby muscles or joints.  It is described as a sharp pain that occurs in one area of the breast (  With non-cyclical mastalgia the pain is present all the time.  If the cause of non-cyclical mastalgia can be located, such as a cyst, then the pain is easier to alleviate. 

Cyclic mastalgia is typically associated with the menstrual cycle and is normally related to hormone levels in a woman’s body.  With cyclical mastalgia, the pain felt in the breast is not permanent.  It normally comes and goes and the doctor recommends that the woman charts her pain in order to determine the pattern of occurrence ( There are levels of pain and discomfort varying from barely noticeable to extremely severe.  In its severity, cyclical mastalgia can prevent a woman from wearing tight fitting clothing and inhibit any contact to the breast.  Due to the varying levels of pain, not all women need treatment.  It is generally necessary to reassure the woman that she does not have breast cancer.  After this initial reassurance only women that experience pain that affects their quality of life need to seek treatment with either pharmaceuticals or alternative therapies like evening primrose oil.



Is Evening Primrose Oil Effective in Treating Mastalgia?


Four studies will be reviewed in order to assess the effect of evening primrose oil on both cyclical and non-cyclical mastalgia. 



The first study was conducted in the Cardiff mastalgia clinic by the University of Wales College of Medicine and published in the Journal of the Royal Society of Medicine in 1992.

The researchers at the clinic require that new patients make a breast pain chart for a period of two menstrual cycles.  With this chart the researchers produced a baseline measuring the severity of pain.  The chart also enables the researchers to distinguish between cyclical and non-cyclical mastalgia. This is important because medication is generally less effective with non-cyclical mastalgia.  

Over the course of 17 years 490 patients were given one of the following treatments for their pain: danazol 200mg daily, bromocriptine 5mg daily, or evening primrose oil 6X500mg capsules daily.  The choice of the most appropriate treatment is made with the patient so that they are aware of any adverse side effects. Of the 490 patients, 375 had cyclical mastalgia and 115 had non-cyclical.

324 patients with cyclical mastalgia and 90 patients with non-cyclical mastalgia completed a therapeutic trial.  With evening primrose oil a therapeutic trial lasted 4 months, whereas with danazol and bromocriptine the trial lasted 2 months. If the treatment was successful then it was stopped after a period of 6 months. 


The following chart summarizes the results of the study for cyclical mastalgia



Patients Receiving Treatment

Successfully treated (%)







Evening Primrose Oil




The following chart summarizes the results of the study for non-cyclical mastalgia


Patients Receiving Treatment

Successfully treated (%)







Evening Primrose Oil




Both danazol (30%) and bromocriptine (35%) had more recorded adverse effects than evening primrose oil (4%).


The study concluded that in terms of general effectiveness danazol was the most effective with evening primrose oil and bromocriptine having relatively equivalent efficacy rates.  However, unless the patient requires a rapid response to pain, evening primrose oil should be the first treatment option since it causes considerably less adverse effects. (



            The second study is similar to the first in that it compares the effectiveness of danazol, bromocriptine and evening primrose oil.  It was carried out by Pye, Mansel, and Hughes in 1985. 

            The design of the study was a randomized trial in open studies of 291 patients who were suffering from severe breast pain. 77% of the patients suffered from cyclical mastalgia while 44% suffered from non-cyclical mastalgia. 

            The results are summarized in the following chart for cyclical mastalgia



Successfully treated (%)





Evening Primrose Oil



            The results for patients with non-cyclical mastalgia are summarized below.




Successfully treated (%)





Evening Primrose Oil



            This study demonstrated similar results to the first study in that all methods of treatment are relatively successful.  There is not a significant difference between bromocriptine and evening primrose oil when looking at cyclic mastalgia.  In non-cyclical mastalgia all three treatments are relatively close. 




The third study looked at the effect of evening primrose oil and fish oil on severe chronic mastalgia.  The Department of Clinical Epidemiology and Biostatistics, Vrije Universiteit University Medical Center in Amsterdam carried out the study, specifically Bloomers et al.  This study was published in 2002 in the Amsterdam Journal of Obstetricians and Gynecologists.

 The design of the study is as follows.  It was a randomized, double-blind, controlled study.  The study was a factorial clinical trial, which means that the two methods of treatment, evening primrose oil and fish oil, were studied simultaneously. 120 women were randomly placed into 4 groups.  The first group was the fish oil and control oil, second group was evening primrose oil and control oil, the third group was fish and evening primrose oil and the final group was both control oils.  The study lasted 6 months.  The control oils were corn oil and corn oil with wheat germ.  After 6 months the number of days with breast pain was compared to the number of days with pain before treatment began. 

The results are displayed in the following table with each percentage representing the decrease in days for each treatment and control.



Decrease in Days %

1. Fish Oil


2. Control oil for Fish oil


3. Evening primrose oil


4. Control oil for evening primrose oil



            The results demonstrate that all methods of treatment were successful in reducing the number of days of pain felt; however, no method is significantly more effective than another.  Therefore, while evening primrose was effective, it was not more effective than the control of corn oil.  (





The fourth study, conducted by Goyel, Mansel and the Efamast Study Group looked at the effect of evening primrose oil, with and without antioxidants, in the management of mastalgia.  The study was published in 2005 in the Breast Journal from the Department of Surgery at the Wales College of Medicine in Cardiff, UK.

The study was a randomized, “double-blind, placebo-controlled, parallel group, multicenter study” (see link below).  The study included 555 patients suffering from varying levels of mastalgia. Each patient was randomized into one of four groups. The first group received evening primrose oil and antioxidants, the second received placebo fatty acids and antioxidants.  The third group received evening primrose oil and placebo antioxidants and the last group received placebo fatty acids and placebo antioxidants.  The groups were charted for four menstrual cycles based on their group.  After the first four cycles, all patients received evening primrose oil with the independent variable being the active or placebo antioxidants. 

The results showed that all four groups showed a reduction in their mastalgia.  Therefore, the effect of evening primrose oil does not differ from the placebo of fatty acids.  (




What Does All This Mean?


When looking specifically at the dates of the studies mentioned, it is clear that as the studies have progressed, not only have they become more sophisticated in their methods (i.e. using randomized double-blind studies that evenly disperse confounding variables), but they collectively say that while evening primrose may help, it is not more effective than placebo effect (control oils).   Evening primrose oil unquestioningly reduces pain in women suffering from mastalgia; however, there are other treatments available that are more effective.  Clearly stated, evening primrose oil has not been sufficiently demonstrated to be more effective than receiving fatty acids from foods such as sunflower seeds, pumpkin seeds, safflower oil, most nuts, vegetables and grains. 


















Additional Research


Challem, Jack.  What Herbs Are All About.  Keats Publishing Inc, 1980.


Passwater, Richard A. Evening Primrose Oil.  Keats Publishing Inc, 1981. 





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