A handful of supplements show modest benefits for hot flashes, but none are as effective as hormone therapy, and most major medical organizations stop short of recommending them. The most consistent evidence supports soy isoflavone extracts, which reduced hot flash frequency by about 17% and severity by about 31% in pooled clinical trials. Other options like red clover and black cohosh have weaker or more mixed results. Here’s what the research actually shows for each one.
Soy Isoflavones Have the Strongest Evidence
Soy isoflavones are plant compounds that weakly mimic estrogen in the body. Among all the supplements studied for hot flashes, soy isoflavone extracts have the most consistent track record. A meta-analysis of 13 placebo-controlled trials involving nearly 1,200 women found that supplemental soy isoflavone extract (30 to 80 mg per day, taken for six weeks to one year) reduced hot flash frequency by 17.4%. A separate analysis of nine trials found a 30.5% reduction in hot flash severity at similar doses.
Not all soy products work equally well. A 2013 Cochrane review found that supplements containing primarily genistein, a specific isoflavone, at 30 to 60 mg per day significantly reduced hot flash frequency. But dietary soy (like tofu or soy milk), mixed soy isoflavone extracts, and red clover extracts did not show the same benefit in that review. If you’re considering soy supplements, look for products that list genistein content specifically.
There’s an interesting wrinkle with soy: your gut bacteria determine how well it works. Your body needs certain intestinal bacteria to convert soy compounds into a metabolite called S-equol, which appears to be the active ingredient behind the benefits. Only about 50% of Asian women and 25% of non-Asian women naturally host these bacteria. For women who can’t produce S-equol on their own, direct S-equol supplements exist, though the clinical evidence for them is still limited and comes mostly from small trials in Japanese women.
Red Clover Works Short-Term, Then Fades
Red clover contains isoflavones similar to those in soy, and it does appear to help, but only temporarily. A meta-analysis found that red clover extract reduced hot flashes by about 1.3 episodes per day compared to placebo when taken for three to four months. That’s a meaningful difference for someone having several hot flashes daily.
The catch: this benefit disappeared at the 12-month mark. Women taking red clover for a year showed no significant difference from those on placebo. This suggests red clover may offer short-term relief but isn’t a lasting solution. If you try it, give it three to four months to evaluate whether it’s helping, and don’t expect permanent results.
Black Cohosh: Popular but Unproven
Black cohosh is one of the most widely marketed supplements for menopause symptoms, but the clinical evidence is disappointing. In a randomized controlled trial of 69 women with breast cancer experiencing hot flashes, black cohosh performed no better than placebo, whether the hot flashes were caused by medication or natural menopause.
Beyond the question of effectiveness, black cohosh carries a safety concern worth knowing about. The UK’s medicines regulatory agency concluded that the available evidence supports a link between black cohosh and liver injury. The risk is considered rare (roughly between 1 in 1,000 and 1 in 10,000 users), and most liver reactions occur within the first three months of use. Anyone with a history of liver problems should avoid it entirely. If you do try black cohosh, watch for symptoms like unusual fatigue, dark urine, or yellowing of the skin, which could signal liver trouble.
Omega-3s Help Night Sweats, Not Hot Flashes
Omega-3 fatty acid supplements are sometimes recommended for menopause symptoms, but the evidence splits in an unexpected way. A systematic review and meta-analysis found that omega-3 supplements had no benefit for hot flash frequency, hot flash severity, sleep quality, or overall quality of life during menopause.
What they did help with was night sweats specifically. Women taking omega-3s experienced significantly lower frequency and severity of night sweats compared to placebo. If your main complaint is waking up drenched at night rather than daytime hot flashes, omega-3s may be worth trying. But if daytime hot flashes are your primary concern, don’t expect much.
What Medical Guidelines Actually Say
The North American Menopause Society’s 2023 position statement on nonhormone therapies does not recommend supplements or herbal remedies for hot flashes. This includes soy foods, soy extracts, the S-equol metabolite, and herbal supplements broadly. The recommendation is based on the overall inconsistency of evidence and the relatively modest effect sizes compared to prescription options.
That doesn’t mean these supplements are useless for every individual. It means the evidence isn’t strong or consistent enough for a medical society to endorse them as standard treatment. For women who can’t or prefer not to use hormone therapy or prescription alternatives, the 17% to 31% improvement seen with soy isoflavones may still be worthwhile, even if it falls short of what medication can achieve.
Safety With Hormone-Sensitive Conditions
Because soy and red clover isoflavones act like weak estrogens, women with a history of hormone-sensitive cancers often worry about safety. The evidence here is more reassuring than you might expect. MD Anderson Cancer Center states there’s no reason to avoid eating soy foods, and research suggests soy foods may actually reduce the risk of cancer recurrence, even in women with estrogen-receptor-positive breast cancer.
Supplements are a different story. They can contain much larger doses than food sources, may include impurities or additives, and can interact with medications. MD Anderson recommends caution with soy supplements specifically because they aren’t well regulated by the FDA and may contain doses that differ significantly from what’s listed on the label.
How Long to Wait Before Judging Results
Most clinical trials showing benefits from soy isoflavones ran for at least 12 weeks, and some lasted a full year. If you start a supplement, give it at least three months before deciding whether it’s working. Hot flash frequency naturally fluctuates from week to week, so a few good days early on don’t necessarily mean the supplement is responsible, and a few bad days don’t mean it’s failed.
Keep a simple log of how many hot flashes you have per day and how intense they are. After 12 weeks, compare your averages to your first couple of weeks. If you’re seeing meaningful improvement, it may be worth continuing. If nothing has changed after three to four months, the supplement probably isn’t going to help you, and it’s worth exploring other options with your healthcare provider.