Best Supplements for Hot Flashes During Perimenopause
The best supplements for hot flashes during perimenopause, including black cohosh, sage, phytoestrogens, magnesium, and evening primrose oil.
Why Hot Flashes Happen in Perimenopause
Hot flashes are among the most common symptoms of perimenopause, affecting around 75 percent of women going through the transition. They happen because fluctuating estrogen disrupts the hypothalamus, the part of the brain that regulates body temperature. Even small changes in core temperature can trigger a sudden flush of heat, sweating, and a racing heart. For many women, hot flashes peak in the year or two around the final menstrual period and can persist for several years. Supplements cannot replicate the effects of hormone therapy, but several have meaningful evidence behind them for reducing frequency and intensity.
Black Cohosh
Black cohosh (Actaea racemosa) is the most researched herbal supplement for hot flashes. Multiple randomised trials show it reduces hot flash frequency and severity compared with placebo. The standard dose is 20 to 40 mg of a standardised extract twice daily. Most studies use it for up to 6 months, and guidelines generally suggest not exceeding that without medical advice. Rare cases of liver problems have been reported, so women with existing liver conditions should avoid it or check with a doctor first. It is not a phytoestrogen and does not appear to act on estrogen receptors, making it an option for women who prefer to avoid estrogenic compounds.
Sage
Sage (Salvia officinalis) has a long traditional use for menopausal hot flashes and sweating, and some clinical trials support this. A standardised sage extract at 280 mg per day was shown to reduce hot flash frequency significantly over 8 weeks in one well-cited study. Sage appears to work through the nervous system rather than through estrogen pathways. It is generally well tolerated. Avoid high doses of sage essential oil, which contains thujone and can be toxic. Stick to standardised tablet or capsule forms. Sage tea is a lower-dose option for mild symptoms.
Phytoestrogens: Soy Isoflavones and Red Clover
Phytoestrogens are plant compounds that weakly mimic estrogen in the body. The two most studied forms are soy isoflavones and red clover isoflavones. A meta-analysis in Menopause showed that soy isoflavones at 40 to 80 mg per day reduced hot flash frequency by around 20 percent compared with placebo. Red clover is richer in the isoflavone formononetin and shows similar modest benefits. Both are generally safe for healthy women, but women with a history of hormone-sensitive cancers should discuss use with their oncologist before starting. Effects take 8 to 12 weeks to build. Food sources like tofu, edamame, and tempeh also contribute phytoestrogens.
Magnesium
Magnesium has limited but growing evidence for reducing hot flash frequency, particularly in women who cannot or prefer not to use estrogen. A pilot study in breast cancer survivors found magnesium oxide at 400 to 800 mg per day cut hot flash frequency by around 40 percent. Magnesium also supports sleep and reduces anxiety, which matters because hot flashes at night (night sweats) are a major driver of poor sleep in perimenopause. Magnesium glycinate is better tolerated than oxide for most people, causing less loose stool. Start at 200 mg in the evening and increase gradually.
Evening Primrose Oil
Evening primrose oil (EPO) is rich in gamma-linolenic acid (GLA), an omega-6 fatty acid with anti-inflammatory properties. Some small studies suggest it may reduce hot flash severity, though the evidence is less robust than for black cohosh or phytoestrogens. A dose of 500 to 1000 mg per day is commonly used. EPO is generally well tolerated; the most common side effects are mild nausea and loose stools. It may increase bleeding risk slightly, so caution is needed before surgery or if taking blood thinners. EPO is often seen as an add-on rather than a first-line choice.
What to Try First and How to Track Progress
If you are unsure where to start, black cohosh is the most evidence-backed option for hot flash reduction in women without liver conditions. Phytoestrogens are a good second choice, especially if you already eat a plant-rich diet. Magnesium is worth adding regardless because of its broader benefits for sleep and mood. Give any supplement at least 8 to 12 weeks before judging its effect. Keeping a symptom log helps you see whether things are improving. The PeriPlan app lets you log symptoms and track patterns over time, so you can spot whether frequency or intensity is changing week by week. Always tell your GP what supplements you are taking, especially if you are on other medications.
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