Quercetin is a plant pigment (flavonoid). It is found in many plants and foods, such as red wine, onions, green tea, apples, berries, Ginkgo biloba, St. John's wort, American elder, and others. Buckwheat tea has a large amount of quercetin. People use quercetin as a medicine.

Quercetin is most commonly taken by mouth to treat conditions of the heart and blood vessels and prevent cancer. It is also used for arthritis, bladder infections, and diabetes. But there is limited scientific evidence to support these uses.

Coronavirus disease 2019 (COVID-19): Quercetin may have benefit for some airway infections, but there is no good evidence to support using it for COVID-19. Follow healthy lifestyle choices and proven prevention methods instead.


Is a Form of:

Plant pigment

Primary Functions:

Heart conditions, blood vessels, cancer

Also Known As:

Bioflavonoid Concentrate, Bioflavonoid Extract, Bioflavonoïde, Bioflavonoïde de Citron

How Does It Work?

Quercetin has antioxidant and anti-inflammatory effects which might help reduce inflammation, kill cancer cells, control blood sugar, and help prevent heart disease.


  • Athletic performance.Most clinical research shows that taking quercetin before exercise does not decrease fatigue or improve exercise ability.

Recommended Dosing

The appropriate dose of quercetin depends on several factors such as the user's age, health, and several other conditions. At this time there is not enough scientific information to determine an appropriate range of doses for quercetin. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult your pharmacist or physician or other healthcare professional before using.

Quercetin Supplements Frequently Asked Questions

What is quercetin used for?

People use quercetin as a medicine. Quercetin is most commonly taken by mouth to treat conditions of the heart and blood vessels and prevent cancer. It is also used for arthritis, bladder infections, and diabetes.

Is Quercetin safe to take daily?

When you take it as a food, quercetin is likely safe. As a supplement, quercetin may be safe if you take reasonable amounts for a short time, such as 500 milligrams twice a day for 12 weeks.

What are the side effects of quercetin?

Common side effects of quercetin include:

  • Headache (oral use)
  • Numbness and tingling (oral use)
  • Shortness of breath (intravenous use)
  • Nausea and vomiting(intravenous use)
  • Kidney damage(intravenous use greater than 945 mg/m2)

Who should not take quercetin?

You should take periodic breaks from taking quercetin. Pregnant women, breastfeeding women, and people with kidney disease should avoid quercetin. At doses greater than 1 g per day, there have been reports of damage to the kidneys.

Is CoQ10 the same as quercetin?

Antioxidants, such as coenzyme Q10 (CoQ10) and quercetin, a member of flavonoids present in red wine and tea, are thought to play a significant role in protecting cells from oxidative stress induced by reactive oxygen species (ROS).

What food has the most quercetin?

Quercetin is the most abundant flavonoid in the diet. It's estimated that the average person consumes 10–100 mg of it daily through various food sources. Foods that commonly contain quercetin include onions, apples, grapes, berries, broccoli, citrus fruits, cherries, green tea, coffee, red wine, and capers.

How quickly does quercetin work?

One published abstract 14 reported that 3 weeks of quercetin supplementation protected against mental fatigue and loss of sustained vigilance following 3 days of heavy exercise.

Does quercetin cause anxiety?

Quercetin is a bioflavonoid reported to produce variety of behavioral effects like anxiolytic, antidepressant, etc. As CRF is commonly implicated in the high-anxiety and depression, we hypothesized that quercetin may involve CRF in its anxiolytic- and antidepressant-like effects.

Does quercetin cause weight gain?

Quercetin is a flavonoid which activates oxidative metabolism. Quercetin may reduce weight gain by decreasing feed efficiency. Weight gain of the QT group decreased when compared with the PT and PS groups. Exercised groups increased cumulative caloric intake during the experimental period.

Is Quercetin an immune booster?

Appropriate nutritional supplementation can be one immune boosting strategy and one such promising product appears to be quercetin. Quercetin is a powerful antioxidant, anti-histamine and anti-inflammatory, and is the most prominent of over 5,000 flavonoid compounds found in food.

Can quercetin cause kidney damage?

Quercetin is generally considered safe. Very high doses of quercetin may damage the kidneys. You should take periodic breaks from taking quercetin. Pregnant women, breastfeeding women, and people with kidney disease should avoid quercetin.

Is Quercetin a vitamin C?

Background: Quercetin, which is considered as a health-promoting antioxidant, belongs to the broad flavonoids group. Numerous experimental studies have proved that quercetin and vitamin C provide anti-inflammatory and antioxidant properties.

Does quercetin keep you awake?

Abstract. The bioflavonoid quercetin is widely found in plants and exerts a large number of biological activities such as anti-hypertensive and anti-inflammatory properties. Therefore, the present results suggest that quercetin alters the sleep-wake cycle partly through activation of GABA(A) receptors.

What medications does quercetin interact with?

Interactions. Be careful if you are taking drugs such as antibiotics, cyclosporine, warfarin, or drugs that are changed by the liver. Quercetin may change how these drugs work and raise the risk of side effects. There don't appear to be interactions between quercetin and foods or other herbs and supplements.

Does turmeric contain quercetin?

Curcumin is a flavonoid polyphenol that is the active ingredient in the spice turmeric. Quercetin is one of the most abundant dietary flavonoids and is found in many fruits, vegetables, and beverages.

How much is too much quercetin?

Very high doses of quercetin may damage the kidneys. You should take periodic breaks from taking quercetin. Pregnant women, breastfeeding women, and people with kidney disease should avoid quercetin. At doses greater than 1 g per day, there have been reports of damage to the kidneys.

How does quercetin help immune system?

Quercetin is known for its antioxidant activity in radical scavenging and anti-allergic properties characterized by stimulation of immune system, antiviral activity, inhibition of histamine release, decrease in pro-inflammatory cytokines, leukotrienes creation, and suppresses interleukin IL-4 production.

How much quercetin can I take daily?

If people take quercetin as a supplement, the most common dose is 500 mg per day, but some people can take up to 1,000 mg per day.

What foods contain quercetin?

Quercetin is contained in abundance in apples, honey, raspberries, onions, red grapes, cherries, citrus fruits, and green leafy vegetables [2]. Among vegetables and fruits, quercetin content is highest in onions.

Does quercetin affect thyroid?

Furthermore, quercetin decreases TSH-modulated RNA levels of the thyroid-restricted gene sodium/iodide symporter (NIS). The data raise the possibility that quercetin may be a novel disruptor of thyroid function, which has potential effects on, or use in, the therapy of thyroid diseases.

Do bananas have quercetin?

Bananas are a great source of the super-protective compounds kaempferol and quercetin. These compounds have been extensively studied, and are known to protect cells, reduce inflammation, fight numerous types of tumors, protect nerves, enhance blood circulation, and reduce the risk of a number of diseases.

Does coffee contain quercetin?

Taken together the data strongly suggests that quercetin is the major neuroprotective and anti-inflammatory component in coffee and not caffeine. Drinking 4-5 cups a day could prove beneficial as a preventative for Alzheimer's and Parkinson's disease.

Clinical Studies