Quercetin for Cancer

Quercetin for Cancer: What It Is, How It May Help, and Safety

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Nancy Hepp, MS

past Lead Researcher

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Ms. Hepp is a researcher and communicator who has been writing and editing educational content on varied health topics for more than 20 years. She serves as lead researcher and writer for CancerChoices and also served as the first program manager. Her graduate work in research and cognitive psychology, her master’s degree in instructional design, and her certificate in web design have all guided her in writing and presenting information for a wide variety of audiences and uses. Nancy’s service as faculty development coordinator in the Department of Family Medicine at Wright State University also provided experience in medical research, plus insights into medical education and medical care from the professional’s perspective.

Nancy Hepp, MS past Lead Researcher

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Laura Pole, MSN, RN, OCNS

Senior Clinical Consultant

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Laura Pole is senior clinical consultant for CancerChoices. Laura is an oncology clinical nurse specialist who has been providing integrative oncology clinical care, navigation, consultation, and education services for over 40 years. She is the co-creator and co-coordinator of the Integrative Oncology Navigation Training at Smith Center for Healing and the Arts in Washington, DC. Laura also manages the “Media Watch Cancer News That You Can Use” listserv for Smith Center/Commonweal. In her role as a palliative care educator and consultant, Laura has served as statewide Respecting Choices Faculty for the Virginia POST (Physician Orders for Scope of Treatment) Collaborative as well as provided statewide professional education on palliative and end-of-life care for the Virginia Association for Hospices and Palliative Care.

For CancerChoices, Laura curates content and research, networks with clinical and organizational partners, brings awareness and education of integrative oncology at professional and patient conferences and programs, and translates research into information relevant to the patient experience as well as clinical practice.

Laura sees her work with CancerChoices as a perfect alignment of all her passions, knowledge and skills in integrative oncology care. She is honored to serve you.

Laura Pole, MSN, RN, OCNS Senior Clinical Consultant

Last update: April 6, 2026

Quercetin for cancer: what you need to know

• Quercetin is found in many plant-based foods and is available as a supplement.
• Studies not specific to cancer show lower markers of inflammation and lower blood pressure among people treated with quercetin.
• People eating higher levels of quercetin in foods may have lower risks of some types of cancer.
• Quercetin can interact with some chemotherapy drugs, consult with your healthcare provider before adding to your regimen.
• This is not a standalone treatment for cancer; it is a complementary therapy used alongside standard medical care to support treatment and/or well-being.

What is quercetin?

Quercetin is a natural substance (flavonoid) found in many plant-based foods and available as a supplement. Some foods containing quercetin:

Quercetin is also found in some medicinal plants such as ginkgo biloba, Elderberry, and St. John’s Wort.

As a natural antioxidant, quercetin’s main benefit related to cancer is better body terrain, and especially lower inflammation. People eating higher levels of quercetin in foods may have lower risks of some types of cancer.

Safety

• Supervision by a medical professional is essential
• Known interactions, including with some chemotherapy drugs: consult with your healthcare provider before adding to your regimen
• Quercetin showed few and generally mild side effects in clinical trials

See full safety details ↓

How quercetin may help people with cancer

Strength of evidence rating

Optimizing your body terrain

Many studies show lower markers of inflammation among people with various noncancer health conditions treated with quercetin.⁶Tabrizi R, Tamtaji OR et al. The effects of quercetin supplementation on lipid profiles and inflammatory markers among patients with metabolic syndrome and related disorders: a systematic review and meta-analysis of randomized controlled trials. Critical Reviews in Food Science and Nutrition. 2020;60(11):1855-1868; Ou Q, Zheng Z, Zhao Y, Lin W. Impact of quercetin on systemic levels of inflammation: a meta-analysis of randomised controlled human trials. International Journal of Food Sciences and Nutrition. 2020;71(2):152-163; Mohammadi-Sartang M, Mazloom Z, Sherafatmanesh S, Ghorbani M, Firoozi D. Effects of supplementation with quercetin on plasma C-reactive protein concentrations: a systematic review and meta-analysis of randomized controlled trials. European Journal of Clinical Nutrition. 2017;71(9):1033-1039; Javadi F, Ahmadzadeh A et al. The effect of quercetin on inflammatory factors and clinical symptoms in women with rheumatoid arthritis: a double-blind, randomized controlled trial. Journal of the American College of Nutrition. 2017 Jan;36(1):9-15. People with metabolic syndrome and related disorders treated with quercetin showed lower fasting plasma glucose, but no evidence of an effect on HbA1ca form of hemoglobin, a protein in red blood cells, that is bound to sugar (glycated hemoglobin). Levels of HbA1c in the blood indicate the average level of blood sugar during the prior two to three months. levels or a marker of insulin resistance, in a combined analysis of studies.⁷Ostadmohammadi V, Milajerdi A, Ayati E, Kolahdooz F, Asemi Z. Effects of quercetin supplementation on glycemic control among patients with metabolic syndrome and related disorders: a systematic review and meta-analysis of randomized controlled trials. Phytotherapy Research. 2019 May;33(5):1330-1340. In a small study of overweight or obese women with polycystic ovary syndrome treated with quercetin, there was no evidence of an effect on fasting blood glucose or insulin.⁸Khorshidi M, Moini A et al. The effects of quercetin supplementation on metabolic and hormonal parameters as well as plasma concentration and gene expression of resistin in overweight or obese women with polycystic ovary syndrome. Phytotherapy Research. 2018 Nov;32(11):2282-2289. Treatment with quercetin was not seen to influence measures of body weight among overweight or obese people in a combined analysis of studies.⁹Huang H, Liao D, Dong Y, Pu R. Clinical effectiveness of quercetin supplementation in the management of weight loss: a pooled analysis of randomized controlled trials. Diabetes, Metabolic Syndrome and Obesity: Targets and Therapy. 2019 Apr 24;12:553-563.

In two small studies not specific to cancer, people treated with quercetin showed lower markers of oxidative stress.¹⁰Duranti G, Ceci R et al. Chronic consumption of quercetin reduces erythrocytes oxidative damage: Evaluation at resting and after eccentric exercise in humans. Nutrition Research. 2018 Feb;50:73-81; Boots AW, Drent M, de Boer VC, Bast A, Haenen GR. Quercetin reduces markers of oxidative stress and inflammation in sarcoidosis. Clinical Nutrition. 2011 Aug;30(4):506-12. Small studies showed changes in hormone levels (lower levels of testosterone, luteinizing hormone, and resistin and higher levels of adiponectin) among women with polycystic ovary syndrome treated with quercetin.¹¹Khorshidi M, Moini A et al. The effects of quercetin supplementation on metabolic and hormonal parameters as well as plasma concentration and gene expression of resistin in overweight or obese women with polycystic ovary syndrome. Phytotherapy Research. 2018 Nov;32(11):2282-2289; Rezvan N, Moini A et al. Effects of quercetin on adiponectin-mediated insulin sensitivity in polycystic ovary syndrome: a randomized placebo-controlled double-blind clinical trial. Hormone and Metabolic Research. 2017 Feb;49(2):115-121. One small study showed less blood clotting among people with advanced cancer at high risk for blood clots treated with isoquercetin.¹²Zwicker JI, Schlechter BL et al. Targeting protein disulfide isomerase with the flavonoid isoquercetin to improve hypercoagulability in advanced cancer. JCI Insight. 2019;4(4).

Reducing cancer risk or recurrence

A large study found a lower risk of proximal colon cancer among people eating the highest levels of foods with quercetin, including tea, who also had high fruit intake or Healthy Eating Index scores.¹³Djuric Z, Severson RK, Kato I. Association of dietary quercetin with reduced risk of proximal colon cancer. Nutrition and Cancer. 2012;64(3):351-360. In another study, people eating foods with the highest levels of quercetin showed lower risk of stomach cancer, with stronger effects for female smokers.¹⁴Ekström AM, Serafini M et al. Dietary quercetin intake and risk of gastric cancer: results from a population-based study in Sweden. Annals of Oncology. 2011;22(2):438-443. One study found a lower risk of prostate cancer among men with the highest intake of quercetin in foods,¹⁵McCann SE, Ambrosone CB. Intakes of selected nutrients, foods, and phytochemicals and prostate cancer risk in western New York. Nutrition and Cancer. 2005;53(1):33-41. but another study found no evidence of an effect on prostate specific antigen (PSAprostate-specific antigen: a protein produced by both normal and malignant cells of the prostate gland; the blood level of PSA is often elevated in men with prostate cancer) or PSA doubling time among men with elevated PSA levels treated with quercetin.¹⁶Galasso A, Aufderklamm S et al. 800 chemopreventive properties of the flavonoids genistein and quercetin in men with rising psa: first results of a double-blind, randomized, placebo-controlled trial (Quergen Trial). Journal of Urology. 2013 Apr;189(4S):e329. 

In two large studies, women eating foods with higher levels of quercetin showed no evidence of an effect on risk of ovarian cancer.¹⁷Gates MA, Vitonis AF et al. Flavonoid intake and ovarian cancer risk in a population-based case-control study. International Journal of Cancer. 2009 Apr 15;124(8):1918-25; Gates MA, Tworoger SS et al. A prospective study of dietary flavonoid intake and incidence of epithelial ovarian cancer. International Journal of Cancer. 2007 Nov 15;121(10):2225-32.

In one study, people with breast cancer, especially obese people, eating higher levels of foods containing quercetin showed lower incidence of recurrence.¹⁸Cheon M, Chung M, Park Y. Association between dietary intake of flavonoids and cancer recurrence among breast cancer survivors. Nutrients. 2021 Aug 30;13(9):3049.

See the full evidence summary ›

Affordability and access

Is a prescription required?

• No prescription is needed for supplements, but we recommend you consult your oncology team before using quercetin. 

Where to find it

• Quercetin supplements are widely available in retail and online drug stores.

Affordability

• Generally inexpensive (less than $45 US/month)

Find an integrative provider ›

Full safety details

Side effects and adverse reactions

Quercetin is relatively nontoxic and is considered “possibly safe” in oral doses of 500 mg or less.¹⁹TRC Natural Medicines Database. Quercetin: Monograph. Quercetin showed few and generally mild side effects in clinical trials.²⁰Buonerba C, De Placido P et al. Isoquercetin as an adjunct therapy in patients with kidney cancer receiving first-line sunitinib (quasar): results of a phase I trial. Frontiers in Pharmacology. 2018 Mar 16;9:189; Lu NT, Crespi CM et al. A phase I dose escalation study demonstrates quercetin safety and explores potential for bioflavonoid antivirals in patients with chronic hepatitis C. Phytotherapy Research. 2016 Jan;30(1):160-8; Henning SM, Wang P et al. Prospective randomized trial evaluating blood and prostate tissue concentrations of green tea polyphenols and quercetin in men with prostate cancer. Food & Function. 2020 May 1;11(5):4114-4122; Zwicker JI, Schlechter BL et al. Targeting protein disulfide isomerase with the flavonoid isoquercetin to improve hypercoagulability in advanced cancer. JCI Insight. 2019;4(4).   

Drug interactions 

There are known drug interactions with this therapy. Interactions with medications and other interventions are complex. Always consult with a healthcare professional before adding any new therapy to your regimen. To learn more about interactions visit one of the trusted resources below: 

• EfficaSafe ›
• About Herbs ›

Interactions with chemotherapy drugs

Quercetin can interact with some chemotherapy drugs. Be sure to let your oncologist know that you are taking quercetin if you are planning treatment or in treatment with any of these drugs:

• Doxorubicin (Adriamycin) or doxorubicin combined with cyclophosphamide: increases the cytotoxic effect²¹Azizi E, Fouladdel S et al. Quercetin effects on cell cycle arrest and apoptosis and doxorubicin activity in T47D cancer stem cells. Asian Pacific Journal of Cancer Prevention. 2022 Dec 1;23(12):4145-4154; Zhang P, Zhang J, Zhao L, Li S, Li K. Quercetin attenuates the cardiotoxicity of doxorubicin-cyclophosphamide regimen and potentiates its chemotherapeutic effect against triple-negative breast cancer. Phytotherapy Research. 2022 Jan;36(1):551-561; Li S, Zhao Q et al. Quercetin reversed MDR in breast cancer cells through down-regulating P-gp expression and eliminating cancer stem cells mediated by YB-1 nuclear translocation. Phytotherapy Research. 2018 Aug;32(8):1530-1536.
• Paclitaxel: sensitizes paclitaxel-resistant cancer cells²²Wang Y, Yu H et al. Targeted delivery of quercetin by nanoparticles based on chitosan sensitizing paclitaxel-resistant lung cancer cells to paclitaxel. Materials Science and Engineering. C, Materials for Biological Applications. 2021 Feb;119:111442; Koren Carmi Y, Mahmoud H et al. Flavonoids restore platinum drug sensitivity to ovarian carcinoma cells in a phospho-ERK1/2-dependent fashion. International Journal of Molecular Sciences. 2020 Sep 7;21(18):6533; Zhao Q et al. Quercetin reversed MDR in breast cancer cells through down-regulating P-gp expression and eliminating cancer stem cells mediated by YB-1 nuclear translocation. Phytotherapy Research. 2018 Aug;32(8):1530-1536.
• Vincristine: enhances the antitumor effects²³Zhao Q et al. Quercetin reversed MDR in breast cancer cells through down-regulating P-gp expression and eliminating cancer stem cells mediated by YB-1 nuclear translocation. Phytotherapy Research. 2018 Aug;32(8):1530-1536.
• Cisplatin or carboplatin: increases therapeutic effects²⁴Manthalkar L, Ajazuddin, Bhattacharya S. Evidence-based capacity of natural cytochrome enzyme inhibitors to increase the effectivity of antineoplastic drugs. Discover. Oncology. 2022 Dec 26;13(1):142; Xu W, Xie S, Chen X, Pan S, Qian H, Zhu X. Effects of quercetin on the efficacy of various chemotherapeutic drugs in cervical cancer cells. Drug Design, Development and Therapy. 2021 Feb 15;15:577-588.

FAQs

• Can quercetin help fight cancer?
  Evidence on this is very limited; quercetin’s strongest effects are on optimizing body terrain and reducing risk for certain cancers.
• Can quercetin help with cancer side effects?
  There is little research on this. For studies not specific to cancer, quercetin showed benefits in reducing pain (in rheumatoid arthritis and chronic pelvic pain syndrome) and in lowering blood pressure.
• Can quercetin help with reducing cancer risk?
  Studies show different results for different cancers. Quercetin may help reduce risk for proximal colon cancer and stomach cancer, and also reduce recurrence for people with breast cancer. No effect was seen in studies on ovarian cancer, and results were mixed for prostate cancer.
• Does quercetin support immune function in cancer patients?
  There are no studies investigating whether quercetin supports immune function in cancer patients.
• Can quercetin reduce inflammation in cancer patients? 
  Many studies show lower markers of inflammation in people treated with quercetin, though the studies are not specific to people with cancer.

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