Does evening primrose oil help hot flashes?

Our verdict: Not recommended as a treatment for hot flashes specifically; a possible but unconfirmed signal for night sweats.

Evening primrose oil is a long-standing botanical remedy marketed for hot flashes and other menopause symptoms. A 2021 randomized controlled trial gave postmenopausal women either evening primrose oil (1,000mg capsule twice daily) or a placebo for 8 weeks, and found no statistically significant difference in hot flash duration, frequency, or severity between the two groups.

The more interesting finding: night sweats were different

The same trial measured night sweats separately from daytime hot flashes, and found a statistically significant reduction in night sweats frequency and severity in the evening primrose oil group. That's worth noting honestly rather than lumping hot flashes and night sweats together as one uniform "doesn't work" verdict.

That said, context matters: this was one small trial, and it was single-blind rather than fully double-blind, which makes it weaker evidence than a large, double-blind trial would be. It's a signal worth future research following up on, not an established, confirmed benefit.

What this means for you

If hot flashes specifically are your main concern, the evidence doesn't support evening primrose oil as an effective treatment. If night sweats are more disruptive than daytime flashes, this trial offers a modest reason for cautious interest, though not strong enough to call it proven. Either way, see our sleepwear for night sweats guide for a practical comfort measure with no such uncertainty attached.

What has stronger evidence

See our non-hormonal treatments overview for Level I prescription and behavioral options for hot flashes, or use our Does it work? evidence checker to compare every graded option.