# Red clover isoflavones

Source: https://onco.cc/technologies/red-clover-isoflavones/  
OnCo record `red-clover-isoflavones` (Technology). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Red clover extracts are sold for menopausal hot flushes. They contain plant oestrogens, and Memorial Sloan Kettering advises people with hormone-sensitive cancers to avoid them. They may also increase bleeding with blood thinners and caused toxicity in a patient receiving methotrexate.

## Summary

Red clover contains isoflavones that act as phytoestrogens, and isoflavone extracts are promoted for menopausal symptoms. Memorial Sloan Kettering's About Herbs entry reports that some trials show improvement in menopausal symptoms over placebo while systematic reviews are mixed. In the laboratory, red clover extract acted as an oestrogen agonist and stimulated growth of oestrogen receptor-positive breast cancer cells, although one isoflavone inhibited aromatase; it also inhibited growth of normal prostate cells and increased resistance of prostate cancer cells to high-dose radiation. MSK lists hormone-sensitive cancers as a contraindication because of oestrogenic activity. Red clover may increase the effects of anticoagulants and antiplatelet drugs; case reports include a subdural haematoma with long-term use and a subarachnoid haemorrhage with a product combining red clover, dong quai and Siberian ginseng. It caused severe vomiting and epigastric pain in a patient receiving methotrexate injections, and preclinical studies show inhibition of several CYP enzymes. For hot flushes after breast cancer, non-hormonal drugs, cognitive behavioural therapy and acupuncture have better support.

## Fields

- Kind: Technology
- Status: phase-2
- Last checked: 2026-11-04
- Also known as: Trifolium pratense; Promensil
- Tags: complementary; supportive-care; evidence:harm
- Principle: Isoflavones such as biochanin A, formononetin, genistein and daidzein bind oestrogen receptors, which is the intended effect for menopausal symptoms and the concern in hormone-sensitive cancers.
- Strengths: Some placebo-controlled trials for menopausal symptoms in women without cancer
- Limitations: Contraindicated in hormone-sensitive cancers; Bleeding case reports; Toxicity with methotrexate

## Sources

- MSK About Herbs: Red clover (page last updated 10 February 2022): https://www.mskcc.org/cancer-care/integrative-medicine/herbs/red-clover

## Connected records

- technologies: [Acupuncture for hot flushes on endocrine therapy](https://onco.cc/technologies/acupuncture-hot-flushes/), [DHEA (dehydroepiandrosterone) supplements](https://onco.cc/technologies/dhea-supplements/), [Dietary supplements during cancer treatment: interactions and harms](https://onco.cc/technologies/dietary-supplements-treatment-interactions/), [Dong quai](https://onco.cc/technologies/dong-quai/), [Evidence-based integrative oncology](https://onco.cc/technologies/integrative-oncology/), [Flaxseed and flaxseed lignans](https://onco.cc/technologies/flaxseed-supplements/), [Saw palmetto](https://onco.cc/technologies/saw-palmetto/), [Soy foods and breast cancer](https://onco.cc/technologies/soy-breast-cancer/)
- cancers: [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/)
- fronts: [Hormonal Therapy](https://onco.cc/fronts/hormonal/), [Supportive Care & Survivorship](https://onco.cc/fronts/supportive-care/)
- drugs: [Methotrexate](https://onco.cc/drugs/methotrexate/)
- bottlenecks: [Toxicity and quality of life are undervalued](https://onco.cc/bottlenecks/b-toxicity-qol/)

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