When hot flashes strike, many women seek gentle alternatives to hormone replacement therapy. Red clover (Trifolium pratense), with its estrogen-like isoflavones, is considered a promising herbal option. However, the research is more complex than advertising suggests. While some studies show significant relief, others have found no difference compared to a placebo. Here's an overview of current research and what to consider when using red clover.
The plant compounds: How red clover works in the body
Red clover, also known as meadow clover, belongs to the legume family and contains a significant amount of isoflavones in its leaves – secondary plant compounds with weak estrogenic effects. The most important isoflavones in red clover are genistein, daidzein, biochanin A, and formononetin.
These so-called phytoestrogens can have effects in the body similar to the female sex hormone estrogen, albeit significantly weaker. They bind primarily to estrogen-β receptors, which are mainly found in non-gonadal tissues such as fat, brain, and endothelium. This is intended to partially compensate for the natural decline in estrogen during menopause and alleviate typical symptoms such as hot flashes.
The contradictory state of research
The scientific evidence regarding the effectiveness of red clover for hot flashes is inconsistent – there are both positive and negative study results.
Studies with positive results
A 2017 Danish randomized, double-blind study examined 62 perimenopausal women experiencing at least five hot flashes per day. For twelve weeks, they received either a red clover supplement containing 34 mg of isoflavones per day or a placebo. The results, objectively determined by 24-hour skin conductance measurements, were as follows:
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After three months, the frequency of hot flashes decreased by about 23%.
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After one year, the intensity decreased by almost 40%.
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The subjectively reported number also decreased significantly more than in the placebo group.
A 2021 meta-analysis of randomized controlled trials concluded that red clover supplementation over three months resulted in an average of 1.7 fewer hot flashes per day —particularly in women experiencing at least five hot flashes daily. Another systematic review from 2016 also found a trend toward a reduction in hot flashes, close to statistical significance.
A prospective randomized placebo-controlled study published in 2024 from Turkey with 75 postmenopausal women also showed improvements in menopausal symptoms (measured with the Menopause Rating Scale) under a daily dose of 80 mg red clover isoflavones.
Studies with negative results
In contrast, several studies have failed to demonstrate a significant effect. The best-known is the Isoflavone Clover Extract (ICE) study from 2003, which involved 252 women suffering from at least 35 hot flashes per week. After twelve weeks, the results showed:
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Promensil® group (approx. 80 mg isoflavones): 41% reduction
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Rimostil® group (approx. 60 mg isoflavones): 34% reduction
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Placebo group: 36% reduction
The differences between the verum and placebo groups were not statistically significant .
Another randomized controlled trial from 2009 with a 12-month intervention period compared red clover, black cohosh, placebo, and hormone replacement therapy. The result after one year:
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Red clover: 57% reduction in hot flashes
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Placebo: 63% reduction
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Hormone replacement therapy: 94% reduction (only significant deviation)
Here too, red clover showed no significant superiority over placebo . However, the authors emphasized that both herbal preparations were safe to use over 12 months.
The role of strong placebo effects
A striking feature of many studies is the high placebo effect – often between 30 and 50%. This significantly complicates the proof of a genuine treatment effect and is a well-known phenomenon in menopause research.
The 2021 meta-analysis: What remains of the evidence?
The most comprehensive evaluation to date is the meta-analysis by Kanadys et al. from 2021, which included 17 randomized controlled trials. The key findings are:
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Red clover supplementation significantly reduces the frequency of hot flashes, especially in women with at least five hot flashes per day.
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The effect is moderate (approximately 1.7 fewer hot flashes per day).
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The effect did not persist in studies with a 12-month follow-up period.
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Over half of the included studies were at least partially funded by manufacturers, which could skew the results.
The authors conclude that red clover may have some effectiveness in treating hot flashes, but further independent studies are needed.
What does the official assessment say?
The European Food Safety Authority (EFSA) found no evidence of isoflavones improving menopausal symptoms based on the submitted scientific studies. Claims regarding the efficacy of soy isoflavones have been prohibited since 2011. The assessments for red clover are on a so-called "on-hold list"—they have been completed by the EFSA but not yet published by the EU.
The consumer advice center points out that Stiftung Warentest rated each of the five red clover products tested as "not very suitable" in August 2015. ÖKO-TEST also came to no better conclusion than "adequate" in May 2018.
What should you pay attention to when using it?
Despite the inconsistent study results, many women use red clover supplements. There are some important points to consider.
Quality and standardization
A crucial problem is the highly variable quality of the products. The composition and dosage of the ingredients can differ considerably. Traditional medicines contain a standardized extract according to the WHO monograph, while dietary supplements are often not standardized.
Dosage recommendations
The German Federal Institute for Risk Assessment (BfR) recommends the following for food supplements containing red clover isoflavones:
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Maximum 43.5 milligrams of isoflavones per day
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Do not exceed a maximum application duration of three months.
In clinical studies, dosages of between 34 and 80 mg of isoflavones per day were most commonly used.
Possible side effects and contraindications
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Side effects : Occasionally mild nausea, very rarely skin rashes (urticaria)
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Interactions : Possible with medications, e.g., with the thyroid hormone thyroxine.
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Absolute contraindications : Do not use in cases of hormone-dependent breast or uterine cancer. Also, only use after consulting a doctor if there is a family history of the disease.
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Pregnancy and breastfeeding : Do not use
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Children and adolescents : Do not use
Important: Inform your doctor if you wish to use red clover products, especially if you regularly take other medications.
Conclusion
Red clover is not a miracle cure for hot flashes, but it can be an option for some women. The research is contradictory: while some studies show a moderate reduction in hot flashes – especially in women more severely affected – others found no difference compared to a placebo. The high placebo effect and the frequent use of pharmaceutical companies to fund studies make a definitive assessment difficult.
Anyone wishing to try red clover should pay attention to quality, adhere to the dosage recommendations of the German Federal Institute for Risk Assessment (BfR), and limit use to three months. Medical consultation is mandatory in cases of hormone-dependent cancers or a family history of cancer. Hormone replacement therapy remains by far the most effective treatment – with its own risks that must be carefully weighed.
Official sources & studies:
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Kanadys W et al.: Meta-analysis of red clover for hot flashes (Nutrients, 2021) – Examine.com
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Tice JA et al.: ICE study on red clover extracts (JAMA, 2003) – German Pharmacists' Journal
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Geller SE et al.: RCT on red clover vs. placebo (menopause, 2009) - PubMed
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Ghazanfarpour M et al.: Systematic review and meta-analysis (J Obstet Gynaecol, 2016) – QxMD
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Consumer Advice Center Bavaria: Red clover isoflavones for menopause? (March 2025)
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Fugh-Berman A et al.: Review of red clover for menopausal women (Menopause, 2001) – PubMed
