Oral micronized progesterone may diminish hot flashes and night sweats in perimenopausal women, new research from Canada reports. The results were presented on March 19 at ENDO 2018, the 100th annual meeting of the Endocrine Society in Chicago.

“Almost a quarter of all women today are in perimenopause. They are often working as well as maintaining a home and caring for children and elders. About 20% of them will need effective treatment for hot flashes and night sweats to continue to be productive,” says lead author Jerilynn C. Prior, MD, a professor in the Department of Medicine of the Division of Endocrinology and Metabolism at the University of British Columbia, in Vancouver, Canada, in a release “Hot flashes and night sweats occur in eight of 10 perimenopausal women (who’ve had a period in the last year). At present, there is no effective therapy for them. Although not scientifically proven to be effective, women are often prescribed the birth control pill for hot flash symptoms, which may not be safe because women’s risks for blood clots and strokes increase with age and weight gain.”

The researchers studied oral micronized progesterone taken every night at bedtime to treat perimenopausal vasomotor symptoms for 3 reasons, Prior says: Progesterone is effective for menopausal hot flashes and night sweats; progesterone levels are lower than normal in perimenopause; and progesterone increases deep sleep and doesn’t cause blood clots.

Prior and her colleagues randomized 189 women throughout Canada: Over three months, 93 received oral micronized progesterone 300 mg at bedtime and 96 received placebo. Both groups were similar at baseline, and overall, two-thirds of the women had skipped a period and almost all (98%) were being awakened twice a week with night sweats.

Self-reported perceived decreases in daytime and nighttime vasomotor symptoms intensity and in night sweats were significantly greater among the women taking oral micronized progesterone than among those on placebo.

By month three, hot flashes and night sweats had decreased in the women in the progesterone group. Although that decrease was not statistically different from placebo, the women taking progesterone experienced a clinically important difference: they perceived that their hot flashes were significantly less intense and that their night sweats were significantly improved, compared with placebo.

Overall, 93% of the women completed the study, and the women were very likely to take their study medication (91.4% of those on progesterone and 84.4% of those on placebo). No increased serious or drug-related side effects were reported.

The Canadian Institutes for Health Research funded the study.