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Quercetin is a compound that gives plants and foods their color. It is found in onions, berries, and teas. Quercetin has been used to improve heart health and athletic performance. It has also been used as an antioxidant to help slow damage to cells. Quercetin can be taken as a pill or powder. It can also be injected into the bloodstream by a healthcare provider.


500 milligrams 1 to 2 times daily

What Research Shows

Likely Effective

  • High Blood Pressure —likely to lower blood pressure A1
  • Metabolic syndrome —may lower fasting plasma glucose B1

May Be Effective

  • Upper respiratory tract infection —may improve symptoms and promote quicker recovery C1

Editorial process and description of evidence categories can be found at EBSCO NAT Editorial Process.

Safety Notes

It is likely safe to take quercetin in small doses for a short time. Not enough studies have been done to say whether it is safe to take for a long period. It is also not known whether it is safe to take by women who are pregnant or breastfeeding.D1


Talk to your doctor about any supplements or therapy you would like to use. Some can interfere with treatment or make conditions worse.



A. High Blood Pressure

A1. Serban MC, Sahebkar A, et al. Effects of Quercetin on Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. J Am Heart Assoc. 2016;5(7):e002713.

B. Metabolic Syndrome

B1. Ostadmohammadi V, Milajerdi A, et al. 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. Phytother Res. 2019 May;33(5):1330-1340.

C. Upper Respiratory Tract Infection

C1. Heinz SA, Henson DA, et al. Quercetin supplementation and upper respiratory tract infection: A randomized community clinical trial. Pharmacol Res. 2010;62(3):237-242.

D. Safety

D1. Andres S, Pevny S, et al. Safety Aspects of the Use of Quercetin as a Dietary Supplement. Mol Nutr Food Res. 2018 Jan;62(1).

Last reviewed September 2019 by EBSCO NAT Review Board Eric Hurwitz, DC  Last Updated: 4/10/2020