Ingredient guide
Evening primrose oil supplies gamma-linolenic acid (GLA), an omega-6 fat. A meta-analysis in menopausal women shows a small reduction in the duration of hot flushes, though not frequency. Older claims for breast pain and atopic eczema have not held up to rigorous review.
Limited evidenceEvening primrose is a North American plant whose seeds yield a yellow oil rich in gamma-linolenic acid, often shortened to GLA. GLA is an omega-6 fatty acid that your body usually makes from linoleic acid in vegetable oils, but it is often supplemented directly. The other common GLA source is borage oil.
GLA in the body is converted into compounds called series-1 prostaglandins, which tend to dampen inflammation, and series-2 prostaglandins, which can do the opposite. The net effect depends on the rest of your fatty acid profile. EPO's claims for skin, breast pain, and menopausal symptoms rest on this anti-inflammatory pathway.
A 2023 systematic review and meta-analysis of 6 randomised trials in 450 menopausal women found that EPO did not significantly reduce the frequency of hot flushes but did reduce their duration. A separate randomised trial reported that 8 weeks of EPO improved psychological symptoms in postmenopausal women compared with placebo.
Older claims for breast pain (mastalgia) and atopic eczema have not held up well in modern reviews, with most large analyses showing little or no benefit. We grade the overall human evidence as limited. EPO has a small case for menopausal symptoms but is not the broad anti-inflammatory cure once claimed.
Standardised oil supplying 80 mg to 320 mg GLA per day, taken with food for 8 weeks or more, fits trial use. Look for products that state the GLA content, not just the total oil. People on blood thinners or seizure medicines should clear it with a healthcare provider first.
Trials commonly use 500 mg to 2,000 mg per day of standardised oil supplying 80 mg to 320 mg GLA, for 8 weeks or more. Take with a meal containing some fat. Ask your healthcare provider before regular use if you take blood thinners or seizure medicine.
A meta-analysis shows shorter hot flush duration but no clear effect on frequency. The benefit is small.
Older trials suggested yes, but larger modern reviews have found little or no benefit. It is no longer recommended for eczema in most guidelines.
GLA is gamma-linolenic acid, an omega-6 fatty acid the body uses to make compounds that modulate inflammation. EPO and borage oil are the main GLA supplement sources.
Generally well tolerated. The main cautions are blood-thinning interactions and a rare effect on seizure threshold.
