Evening Primrose Oil

Native Americans have long valued the evening primrose plant for its healing powers. Today, research focuses on the therapeutic effect of the oil obtained from its seeds, which contain an omega-6 essential fatty acid called gamma-linoleic acid (GLA).

What it is

Called evening primrose because its light yellow flowers open at dusk, this wildflower grows in North America and Europe. The plant and its root have long been used for medicinal purposes – to treat bruises, haemorrhoids, sore throat and stomach aches. But the use of its seed oil, which contains gamma-linoleic acid (GLA), is relatively recent. GLA is an essential fatty acid that the body converts to hormone-like compounds called prostaglandins, which regulate a number of bodily functions.

Although the body can make GLA from other types of seed oils that you consume, there is no one food that has appreciable amounts of GLA. Evening primrose oil provides a concentrated source: 7-10% of its fatty acids are in the form of GLA. There are, however, other sources of GLA. Starflower oil and blackcurrant seed oil contain higher amounts of GLA than evening primrose oil (20-26% for starflower, 14-19% for blackcurrant), but they also have a higher percentage of other fatty acids that may interfere with GLA absorption. Most of the studes investigating the effects of GLA have used evening primrose oil, and for this reason it is the preferred source of GLA. Still, starflower oil may be a good substitute. It’s less expensive than evening primrose oil, and a similar dose is required to produce a therapeutic effect.

What it does

The body produces several types of prostaglandins: some promote inflammation, others control it. The GLA in evening primrose oil is directly converted to important anti-inflammatory prostaglandins, which accounts for most of the supplement’s therapeutic effects. In addition, GLA is an important component of cell membranes.


In people with diabetes, the GLA in evening primrose oil has been shown to help prevent nerve damage (neuropathy), a common complication of the disease. In a study of people with mild diabetic neuropathy, one year of treatment with evening primrose oil reduced numbness and tingling, loss of sensation and other symptoms of the disorder better than a placebo did, suggesting that evening primrose may be of value in reversing neuropathy.

Additional benefits

One of the leading uses of evening primrose oil is to treat eczema, an allergic skin condition that may develop if the body has trouble converting fats derived from food into GLA. Studies of people with eczema indicate that taking evening primrose oil for three to four months can help to alleviate itching and reduce the need for topical steroid creams and drugs (with their unpleasant side effects).

Because of its GLA content, evening primrose oil can be effective for menstrual disorders, such as PMS, menstrual cramps and endometriosis. In particular, the oil blocks the inflammatory prostaglandins that cause menstrual cramps. It also appears to ease the breast tenderness that some women experience just before their periods, and may play a role in reversing infertility in some women.

Rheumatoid arthritis is characterised by joint pain and swelling, and studies have found that these symptoms improve when supplements of evening primrose oil or another source of GLA are taken. Other conditions that involve inflammation, such as rosacea, acne and muscle pain, may also be alleviated by evening primrose oil.

Common uses

  • Eases rheumatoid arthritis pain.
  • Can minimise symptoms of diabetic nerve damage.
  • Relieves eczema symptoms.
  • Helps to treat premenstrual syndrome, endometriosis and menstrual cramps.
  • Lessens inflammation of acne, rosacea and muscle strains.


  • Capsule.
  • Softgel.
  • Oil.

How to take it


The recommended therapeutic dose of evening primrose oil is generally 1000 mg three times daily. This supplies 240 mg of GLA a day. To get an equivalent amount of GLA from other sources, you would need to take 1000 mg of starflower oil or 1500 mg of blackcurrant oil each day. Evening primrose oil or starflower oil can also be applied topically to the fingers to ease the symptoms of Raynaud’s disease.

Guidelines for use

Take evening primrose oil or other sources of GLA with meals to enhance absorption.

Possible side effects

In US studies, about 2% of participants using evening primrose oil experienced bloating or abdomina upset. However, consuming it with food may lessen this effect.