What is Evening Primrose Oil?

Evening primrose oil is extracted from the seeds of evening primrose (evening primrose), a plant native to North America. Its name comes from its yellow flowers that bloom at night.

The oil contains gamma-linolenic acid (GLA) and other omega-6 fatty acids with anti-inflammatory and analgesic or analgesic properties.

This article discusses existing research on evening primrose oil, its common uses, and potential side effects. You’ll also learn about common dosages and how to store them safely.

What is evening primrose oil used for?

Evening primrose oil is not an essential oil commonly used in aromatherapy. Instead, it’s one that can be taken orally.

Alternative healthcare providers believe that evening primrose oil can help treat a variety of health conditions, including skin conditions and nerve and joint pain.

It’s also sometimes used for premenstrual syndrome (PMS), or symptoms that cause menstrual periods, or the transition to menopause or the end of periods.

Many of these potential benefits are attributed to GLA, a fatty acid found in soybeans, walnuts, seeds, and vegetable oils such as canola, canola, and flax.

Some claims are supported by research, but research is generally limited.

menstrual condition

Evening primrose oil is often recommended for cyclical breast pain, which is associated with the menstrual cycle and occurs about a week before your period.

Research on this use is mixed, but 7 of 10 clinical studies included in the 2019 research review showed that evening primrose oil can help relieve breast pain.

For example, one study found that women who took 2 grams (g) of evening primrose oil or 2 g of evening primrose oil plus 400 IU of vitamin E daily for six months had less breast pain severity compared to women who took a placebo There is improvement, or sham treatment.

Evening primrose oil is also sometimes used to treat other symptoms of PMS or to relieve menstrual cramps. However, to date, there is no solid evidence to support these claims.


Evening primrose oil has long been used to treat hot flashes during the menopausal transition. These sudden extreme warm sensations in the upper body are a type of flushing caused by hormonal changes, which may be caused by lower levels of the hormone estradiol.

Although the body of evidence is mixed, it was published in 2013 in Obstetrics and Gynecology Archives Evening primrose oil at a dose of 500 milligrams (mg) per day was found to moderately relieve hot flashes after six weeks.

Although the severity of hot flashes improved compared with those who took a placebo, the duration and frequency of episodes did not.

Evening Primrose Oil and Menopause

skin condition

Eczema, also known as atopic dermatitis, is a skin condition that causes scaly and inflamed skin.

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In the 1980s, evening primrose oil was touted by Canadian entrepreneur David Horrobin as an effective treatment for eczema.

Despite the positive response from consumers, many claims have been debunked by research.

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

Many of the same conclusions were reached when studying the effects of evening primrose oil for psoriasis, which can lead to scaly skin and itchy patches or acne, a condition in which pores become clogged with oil and dead skin cells.

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Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease, a disease in which the immune system attacks its own cells and tissues. With RA, the body primarily attacks its own joints.

Some studies show that GLA can reduce pain and improve function in people with mild to moderate rheumatoid arthritis. However, most results to date have been modest at best.

A 2011 review of Australian studies concluded that GLA, found in evening primrose, borage seed or blackcurrant seed oil, provided modest relief of pain and disability in people with rheumatoid arthritis.

The most promising results were seen in people taking concomitant nonsteroidal anti-inflammatory drugs (NSAIDs), which resulted in slight improvements in morning stiffness and joint movement.

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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, there has been little evidence to support these claims.

This treatment was investigated in a 12-month study from India involving 80 people with severe diabetic neuropathy. It was concluded that taking 500 to 1,000 mg of evening primrose oil and 400 mg of vitamin E daily reduced pain in 88 percent of the participants.

However promising, these conclusions are limited by the lack of a control (placebo) group to make a fair comparison. Still, these findings are important enough to warrant further study.


Increased intake of unsaturated fats is associated with a lower risk of osteoporosis, the loss of bone mineral that causes bones to become weaker and weaker. This condition especially affects postmenopausal women.

Evening primrose oil is composed almost entirely of unsaturated fats, and some believe it can fight bone loss in women with osteoporosis.

An 18-month study from South Africa reported that a combination of evening primrose oil, fish oil, and calcium supplementation slowed or reversed the risk of schizophrenia in older women (average age 79) compared with a control group of women of the same age who took a placebo. Bone loss.

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According to the study, women who received the combination treatment had a 1.3 percent increase in bone mineral density in the femur (thigh) (compared to a 2.3 percent decrease in the placebo group).

While bone density in the lumbar spine or lower back remained the same in the evening primrose oil group, it decreased by 3.2 percent in the placebo group.


There is some very limited evidence to support the use of evening primrose oil for breast pain associated with PMS, hot flashes associated with menopause, arthralgia in patients with rheumatoid arthritis, neuralgia in patients with diabetic neuropathy, or osteoporosis. However, more research is needed.

possible side effects

Like most supplements, there aren’t many studies evaluating evening primrose oil’s long-term safety.

In some cases, evening primrose oil may cause side effects, such as:

  • upset stomach
  • headache
  • nausea
  • diarrhea

Most side effects are low-grade and resolve on their own once treatment is stopped.

Precautions and drug interactions

Tell your healthcare provider if you are taking evening primrose oil or any supplements to avoid drug interactions and potentially serious side effects.

Evening primrose oil should be used with caution if you have certain medical conditions. Among them:

  • Evening primrose oil might increase the risk of bleeding in people with bleeding disorders.
  • If you are about to have surgery, you should stop taking evening primrose oil two weeks in advance to prevent excessive bleeding.
  • Pregnant women should not take evening primrose oil because it may increase the risk of miscarriage or induced labor.

Evening primrose oil can interact with a number of medications, reducing their effectiveness or causing side effects. These include:

  • Anticoagulants (blood thinners) such as coumarin (warfarin), heparin, Lovenox (enoxaparin), Fragmin (dalteparin), and Plavix (clopidogrel)
  • NSAIDs, such as aspirin, Advil (ibuprofen), Aleve (naproxen), and Voltaren (diclofenac)
  • Antipsychotics such as Compro (prochlorperazine), Mellaril (thioridazine), Permatil (fluphenazine), Stelazine (trifluoperazine)​​, and Thorazine (chlorpromazine)
  • HIV medicines, such as lopinavir


Evening primrose oil can interact with some medications, such as blood thinners and NSAIDs. It can also be dangerous for people with certain medical conditions, such as bleeding disorders. Always consult your healthcare provider before taking.

Dosage and Preparation

The U.S. Food and Drug Administration (FDA) regulates supplements differently than pharmaceuticals. Therefore, there is no general guide to the proper use of evening primrose oil.

Generally, 500 mg per day is considered safe for adults, although many can tolerate up to 1,300 mg per day without any side effects.

Due to a lack of research, evening primrose should not be given to children without first consulting a healthcare professional.

Evening primrose oil is available in many health food stores and drugstores. It is usually sold in gel cap form. Bottled evening primrose oil is also available, but it is more difficult to measure accurately.


Evening primrose oil contains a high percentage of unsaturated fats that are susceptible to a breakdown process called oxidative spoilage. If this happens, the quality of the supplement can suffer.

Any product rich in unsaturated oils can go bad, including bottled evening primrose oil and evening primrose oil gel caps.

How long does evening primrose oil last

To extend the shelf life of the oil, keep it in its original container (usually blue to protect from sunlight) and store it in the refrigerator.

Although evening primrose oil stored in this way will keep for up to six months, try to buy only the amount you can use within three months. Due to oxidative deterioration, even in refrigerated conditions, the concentration of seed oil content decreased after three to four months.

How to tell if evening primrose oil has gone bad

Because evening primrose oil has only a faint smell, it’s often difficult to tell if it’s gone bad. It may darken or smell interesting, but not always.

Therefore, you should always be on the safe side and throw away any supplements after their expiry date.


Evening primrose oil usually comes in gel capsule form. There is no standard dose, but about 500 mg to 1,300 mg per day can be taken. To avoid loss of quality, only buy about three months’ supply at a time and store it in the refrigerator.

what to look for

Dietary supplements such as evening primrose oil do not need to undergo the same rigorous testing as drugs.

Instead, the FDA enforces certain standards for the manufacture and labeling of these supplements.

Even so, the quality of supplements like evening primrose oil often varies considerably.

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

If you’re a vegan or vegetarian, only choose brands labeled “Vegetarian Safe” or “Vegetarian Softgels.” Capsules can be made with animal gelatin derived from bovine or porcine, unless clearly stated on the label.


There is some research supporting the use of evening primrose oil in certain pain-causing conditions. But because studies are limited and often mixed, firm conclusions about benefit cannot be drawn.

If you are interested in trying evening primrose oil, be sure to discuss it with your healthcare provider and mention any medications you are taking and your condition to avoid interactions and side effects.