Evening primrose oil: benefits, side effects, interactions


Evening primrose oil is obtained from the seeds of evening primrose ( Oenothera biennis ), a plant native to North America. It gets its name from its yellow flowers that bloom in the evenings. The oil contains gamma-linolenic acid (GLA) , an omega-6 fatty acid that has anti-inflammatory and pain-relieving properties.

Alternative health professionals believe that evening primrose oil can help treat many conditions, including acne, diabetic neuropathy, eczema, osteoporosis, psoriasis, premenstrual syndrome (PMS), and rheumatoid arthritis .

Evening primrose oil is not a commonly used essential oil for aromatherapy and can be taken orally. If consumed in excess, it can cause side effects and interact with certain medications, including blood thinners and non-steroidal pain relievers.

What is evening primrose oil used for?

Evening primrose oil has been touted as an effective treatment for a variety of conditions, including eczema and chest pain, since the 1930s. Many of these potential benefits are attributed to GLA, a fatty acid found in the soybeans, nuts, seeds, and other foods. Vegetable oils (for example, rapeseed, rapeseed and linseed oil). Some claims are better supported by research than others.

Menstrual disorders

Evening primrose oil has long been used by women to treat hot flashes during menopause. Hot flashes are a form of hot flashes caused by reduced levels of the hormone estradiol .

While the evidence remains mixed, a 2013 study from the Archives of Gynecology and Obstetrics found that a 500-milligram daily dose of evening primrose oil produced moderate relief from hot flashes after six weeks.

Although the severity of hot flashes improved compared to women who received placebo , the duration and frequency of the attacks did not change.

Evening primrose oil is also sometimes used to relieve menstrual cramps and PMS. To date, there is no conclusive evidence to support these claims.


In the 1980s, Canadian businessman David Horrobin (1939-2003) widely promoted evening primrose oil as an effective remedy for eczema . Despite the positive response from consumers, many of the claims have been disproven by research.

Evening primrose oil was no more effective in treating atopic eczema than placebo in each of the seven studies reviewed, according to a 2013 University of Minnesota School of Medicine review of studies .

Many of the same findings have been made when investigating the efficacy of evening primrose oil in treating psoriasis or acne.

Rheumatoid arthritis

Rheumatoid arthritis is a type of autoimmune arthritis that mainly affects the joints. Some studies have shown that GLA can reduce pain and improve function in people with mild to moderate rheumatoid arthritis. However, most of the results to date have been modest at best.

A 2011 review of studies in Australia concluded that the GLA found in evening primrose, borage seed, or blackcurrant seed oil provides "moderate" relief from pain and disability in people with rheumatoid arthritis.

The most encouraging results were found in people simultaneously taking nonsteroidal anti-inflammatory drugs , resulting in small improvements in morning stiffness and joints.


A higher intake of unsaturated fats is associated with a reduced risk of osteoporosis (loss of minerals in the bones), especially in postmenopausal women. Evening primrose oil is made up almost entirely of unsaturated fats and is believed by some to counteract the bone loss seen in women with osteoporosis .

An 18-month study in South Africa found that the combined use of evening primrose oil, fish oil, and calcium supplements decreased or reversed bone loss in older women (mean age 79 years) compared to a control group of women aged the same age he received a placebo. …

According to the study, women who received evening primrose oil, fish oil, and calcium experienced a 1.3 percent increase in femur density (compared to a 2.3 percent loss in the placebo group). the spine was unchanged in the evening primrose oil group, and a 3.2 percent decrease in bone density was observed in the placebo group.

Diabetic neuropathy

In 1993, evening primrose oil was first proposed as a possible treatment for diabetic neuropathy , an often debilitating nerve pain that primarily affects the feet and legs. Since then, evidence has emerged to support some of these claims.

A 12-month study in India of 80 people with severe diabetic neuropathy found that a daily dose of 500 to 1,000 milligrams of evening primrose oil, combined with 400 milligrams of vitamin E, helped relieve pain in 88 percent of the participants. .

Promising as they were, the findings were limited by the lack of a control group (placebo) to make an evaluative comparison. However, the results were significant enough to warrant further investigation.

Possible side effects.

As with most dietary supplements, there have been no studies evaluating the long-term safety of evening primrose oil. In some cases, evening primrose oil can cause side effects such as an upset stomach, headache, nausea, and diarrhea. Most side effects are mild and go away on their own after stopping treatment.

Evening primrose oil should be used with caution if you suffer from certain medical conditions. From them:

  • Evening primrose oil may increase the risk of bleeding in people with bleeding disorders or those taking anticoagulants ("blood thinners").
  • If you are having surgery, you should stop taking evening primrose oil two weeks before to avoid excessive bleeding.
  • Pregnant women should not take evening primrose oil as it can increase the risk of miscarriage or artificial delivery.

Drug interactions

Evening primrose oil can interact with a significant amount of medications, reducing the effectiveness of the medication or causing side effects. These include:

  • Blood thinning medications such as fragmin (dalteparin)
  • Blood thinners such as Coumadin (warfarin), heparin, Lovenox (enoxaparin), and Plavix (clopidogrel).
  • Antipsychotics such as Compazine (Prochlorperazine), Mellaril (Thioridazine), Permatil (Fluphenazine), Stelazine (Trifluoperazine), and Thorazine (Chlorpromazine).
  • Non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin, Advil (ibuprofen), Alev (naproxen), and Voltaren (diclofenac).

Inform your doctor if you are taking evening primrose oil or any supplement to avoid drug interactions and potentially serious side effects.

Get Drug Information / Anastasia Tretyak

Dosage and preparation

Since it is a dietary supplement, there is no single recommendation for the proper use of evening primrose oil. Generally speaking, a daily dose of 500 milligrams is considered safe for adults, although many can tolerate up to 1,300 milligrams a day without side effects. Due to a lack of research, evening primrose should not be given to children without first consulting a doctor.

Evening primrose oil is available in many health food stores or pharmacies and is usually sold in gel capsule form. Bottled evening primrose oil is also available, but it is more difficult to dose accurately.

What to look for

Nutritional supplements like evening primrose oil don't have to pass the rigorous testing that pharmaceuticals do. Instead, the US Food and Drug Administration sets specific standards for the manufacture and labeling of additives. However, the quality of supplements, such as evening primrose oil, often varies greatly.

To ensure quality and safety, buy only supplements that are certified by an independent body such as the United States Pharmacopeia (USP), NSF International, or ConsumerLab.

If you are strictly vegan or vegetarian, select only brands that are labeled "vegetarian" or "vegetarian softgels." Unless clearly stated on the label, the capsule can be made from animal gelatin (usually beef or pork).

Other questions

How long does evening primrose oil last?

Evening primrose oil contains a large amount of unsaturated fats, which are susceptible to oxidative deterioration. Because of this, the concentration of oil in the seeds, including the GLA, tends to decrease after three to four months, even when it cools.

To extend the life of your oil, store it in its original container (usually blue to avoid sun exposure) and store it in the refrigerator. Although evening primrose oil can be refrigerated for up to six months, for maximum effectiveness, buy as much as you can use within three months.

How do you know if your evening primrose oil has gone bad?

Any product rich in unsaturated oil can go rancid, including bottled evening primrose oil and evening primrose oil gel capsules. Because evening primrose oil has only a slight odor, it is often difficult to tell if it has gone bad. It may darken or have a strange odor, but not always. Therefore, you should always play it safe and discard any supplements after their expiration date.

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