What is Evening primrose oil?

Evening primrose oil (EPO) had been considered as a panacea in the middle age in Europe for its effect in diverse aspects. North American Indians have used the leaf, stem, flower, and fruit of the evening primrose by grinding and applying them to the affected areas including wounds, skin rashes, and abscesses as therapeutics.
In 1930s, the effects of EPO have been revealed scientifically and the British government has chosen it as a national healthcare medicine. Now it is widely used as a therapeutic for the atopic dermatitis and breast pain. Evening primrose is largely grown in Europe to get its oil from the seed.
Evening primrose is biennial plant in Onagraceae which originated from North America. EPO is composed of 67.5% of linoleic acid, 7.5% of gamma-linolenic acid(GLA), and 25.0% of other fatty acids.

Linoleic Acid

Once absorbed into human body, Linoleic acid is metabolized into various compounds. It is catalyzed by enzymes to become gamma-linolenic acid then converted into dihomogamma-liolenic acid and arachidonic acid afterwards. When dihomogamma-liolenic acid is converted into arachidonic acid, prostaglandin is generated.

Dihomogamma-liolenic acid

It is the reason why we need to uptake EPO. In our bodies, there are many kinds of unsaturated fatty acids including dihomogamma-liolenic acid (GLA). In human body, it is mostly used to synthesize linoleic acid which is vegetable-origin essential fatty acid as a source of prostaglandin.
Dihomogamma-liolenic acid (GLA) can be produced with in a human body as much as needed when healthy. However, it can be short when you drink heavily, take too much animal fats, lack minerals or vitamin B6, or suffer from a disease. When dihomogamma-liolenic acid (GLA) is not synthesized from linoleic acid, deficiency symptoms such as neurodermatitis, rheumatoid arthritis, and others appear.


It is the key compound in controlling blood pressure, blood glucose, and blood cholesterol level. When the level of prostaglandin is low, blood pressure or cholesterol level may increase or allergic diseases such as rhinitis, asthma, and atopic symptoms may appear. In other words, lack of dihomogamma-liolenic acid (GLA) means that the human body is not functioning properly.


EPO has shown effects in some kinds of rheumatoid arthritis as well as inflammatory diseases such as Sjogren’s syndrome and ulcerative colitis. Other than that, it is used to treat neuropathologic diseases of diabetic patients, osteoporosis, acute respiratory distress syndrome (ARDS), hypertension and hyperlipidemia. Also, it has been shown that EPO prevented some kinds of cancer – mostly brain tumor and neuroglioma. It improves the atopic dermatitis, itchiness, and ureteropathy of the patients undergoing blood dialysis.

1. Improve blood circulation

It prevents blood clots and enhances blood circulation by lowering the levels of blood cholesterol and neutral fats

2. Prevent aging

It promotes the generation of prostaglandins which empower the immune system and prevent the clots in blood vessels to eventually contribute to the prevention of aging.

3. Improve menstrual irregularity and relieve menstrual pain and postmenopausal symptoms of women

The level of essential fatty acids is lowered in women with premenstrual syndrome. Prostaglandins induced by dihomogamma-liolenic acids maintain the level of essential fatty acids and relieve premenstrual syndrome by stabilizing the hormonal changes.

4. Maintain healthy skin (Improve dermatitis such as psoriasis, atopic dermatitis, eczema, allergy, and others)

Linoleic acids in EPO are absorbed by skin cells and prevent aging, drying of skin and provide nutrition and vitality for a long time.

5. Prevent obesity

It prevents obesity by stimulating the burn of lipid tissues.

6. Improve cholesterol level

When EPO is administered for long-term, the level of cholesterol is lowered in patients with hyperlipidemia. Especially, it only lowers the level of harmful LDL without influence on the beneficial HDL.

Other than above, it is effective in patients with allergy such as bronchitis, asthma, and rhinitis, osteoporosis, gestational hypertension, and hyperactivity of children.

Cautions and expected side effects

Pregnant women, lactating women, or those with partial history of temporary seizure should avoid using EPO. Also, patients with other types of seizure and those who are administered of neuroleptics such as allphatic phenothiazines should avoid EPO as well. Since EPO has anti-clotting effects, hemophiliac patients or those with hemorrhagic disease and those who are administered of warfarin should give cautions when using EPO. It is contraindicated before undergoing surgery. Since it attenuates lymphocytes, patients with immunodeficiency such as AIDS should be careful in using EPO. Expected side effects include nausea, vomiting, flatulence, diarrhea, and stomach symptoms such as blating. Also, headache has been reported. When used for the complicated symptom of complicated seizure, cautions are needed when using allphatic phenothiaxines (anthelmintics).

Drug interaction

1. Seizure patients treated by neuroleptics

EPO lowers the occurrence of seizure when used with aliphatic phenothiaxines such as chiorpromazine which is the cause of partially complicated heart failure as well as other types of seizures. There is an interaction between EPO and warfarin, aspirin, and NSAIDS. This interaction includes severe nose bleeding, and hematuria. Administration of EPO must be stopped when these symptoms are observed.

2. Nutritional supplements

When EPO is used with anti-thrombopenic supplements such as fish oil, there is interaction between them. It is observed by significantly increased infection, bruise and nose bleeding.

3. Herbs

There is interaction between EPO and herbs such as allium sativa or ginkgo biloba. It is similar to what is described above - easy bruising and nose bleeding.