What Is Quercetin? Health Benefits, Risks, More
Diet & NutritionNutrients & Supplements

Quercetin: Potential Benefits, Known Risks, and More

Quercetin: Potential Benefits, Known Risks, and More
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Updated on October 23, 2025
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Note: The U.S. Food and Drug Administration (FDA) does not approve supplements for safety or effectiveness. Talk to a healthcare professional about whether a supplement is the right fit for your individual health, and about any potential drug interactions or safety concerns.

Quercetin has recently gained attention for its potential to fight inflammation and prevent disease. It’s found in many foods and in supplement form. While it’s generally best to get antioxidants from plant-based foods, you may be wondering if you could benefit from a quercetin supplement.

Potential Health Benefits of Quercetin

Below are some of the potential benefits associated with quercetin, along with some limitations of current research.

Quercetin May Support Heart Health

Thanks to its antioxidant effects, research has investigated quercetin’s potential heart health benefits, such as protecting against atherosclerosis, oxidative stress, hypertension, heart disease, heart attack, and heart failure. But most of the research has been in animals or test tubes, and more human studies are needed to confirm these effects.

“There’s research around quercetin and heart health with good methodology, but it’s limited — we don't have a ton of [human studies] like we do for, say, saturated fats and heart disease,” says Lauri Wright, PhD, RDN, the director of nutrition programs and an associate professor at the University of South Florida College of Public Health in Tampa.

Quercetin May Help Lower Blood Sugar

Test tube and animal studies suggest that quercetin may help support blood sugar management. And researchers have thus posited that for people with type 2 diabetes or prediabetes, quercetin could regulate blood sugar by promoting glucose uptake and improving insulin sensitivity.

But there’s currently a lack of research to confirm these benefits in humans. “Research indicates quercetin can improve insulin sensitivity, potentially benefiting individuals with type 2 diabetes, but we just don't have enough information on the mechanism,” says Dr. Wright. And so far, quercetin supplements are not yet recommended for diabetes management.

Quercetin May Help Prevent Cancer

Test tube and animal studies suggest that quercetin may help prevent cancer by supporting the death of cancer cells and lowering their ability to survive.

“As a flavonoid [plant compound with antioxidant properties], quercetin has been studied for its ability to slow cancer cell growth and reduce inflammation, but more research is needed in humans,” says Wright. Antioxidants, like quercetin, help fight off harmful molecules (known as free radicals) that might otherwise have damaged cells and potentially caused them to become cancerous.

Quercetin May Alleviate Allergies

Quercetin may help with allergy by reducing inflammation and inhibiting histamine production associated with allergies and allergic asthma.

“Quercetin works as a natural antihistamine by stabilizing the cells that release histamine, the culprit behind many allergy symptoms,” says Dawn Jackson Blatner, RDN, the owner of a private practice in Chicago. “While it’s not a magic bullet, some studies suggest it may offer mild relief and be a useful addition to an allergy-management routine.”

In other words, it doesn’t replace allergy medications — and isn’t widely recommended in clinical guidelines or as a first-line treatment for allergies — but getting plenty of quercetin from food might help lessen the severity of your allergic reactions.

May Promote Exercise Recovery in Athletes

Research suggests that quercetin supplements may improve exercise recovery and reduce muscle soreness after intense exercise.

 But research on quercetin for workout recovery is limited to young male athletes. Studies are needed to confirm post-workout benefits for women, older adults, and sedentary individuals.
Overall, because of the lack of research on the benefits of quercetin supplements for exercise recovery, it’s best to consume quercetin from food sources, like a balanced post-workout meal or smoothie.

 “You can get quercetin naturally from foods like apples, onions, blueberries, kale, spinach, green and black tea, and grapes,” says Wright.

May Have Neuroprotective Effects

Thanks to its antioxidant and anti-inflammatory effects, quercetin is also being increasingly studied for its potential to help against neuroinflammation that may lead to conditions like Alzheimer's, Parkinson's disease, and strokes. But research so far has mostly been in lab models. More studies are needed to understand how quercetin supplements may benefit brain health, as well as the optimal dosage.

Weight Loss Effects of Quercetin

Some research suggests that quercetin supplements may reduce some effects of metabolic syndrome in rats, but the findings may not translate to humans.

“There is not enough research to support quercetin supplements for exercise recovery or weight loss,” says Wright.

Quercetin is found in several healthy foods that are part of a balanced diet (like citrus fruits, apples, onions, parsley, sage, tea, grapes, dark cherries, blueberries, and blackberries), Wright adds. And it is well-known that a healthy, balanced diet is essential for both weight loss and exercise recovery.

Potential Risks and Side Effects of Quercetin

As with any supplement, quercetin comes with potential risks and side effects. It’s also important to be aware that the FDA regulates dietary supplements differently from other foods and drug products — supplements are not tested for safety or effectiveness before being available to consumers for sale. Look for products that have been tested and approved by a third party like NSF International or United States Pharmacopeia (USP) and speak to your doctor about any supplement you’re taking.

Wright adds that currently, there’s not sufficient data on appropriate dosages of quercetin supplements that are safe (and may be linked to benefits) for professionals to recommend them. “We also don't know which forms are best absorbed or if supplements work as well as food sources,” she says.

Risks

Quercetin supplements may worsen kidney disease and should be avoided if you have an estrogen-dependent form of cancer, as they may promote tumor development.

Because of the lack of research, quercetin supplements should also be avoided by people who are pregnant or breastfeeding.

Lastly, there are several supplement and drug interactions to be aware of, including the following:

  • Anti-diabetes medications
  • Anti-hypertensive drugs
  • Cyclosporine
  • Diclofenac, a topical and oral medication used in the treatment of arthritis
  • Herbs or supplements that lower your blood sugar, such as chromium
  • Herbs or supplements that lower your blood pressure, such as L-arginine and niacin
  • Midazolam
  • Pravastatin
  • Quinolone antibiotics
  • Quetiapine
  • Warfarin

Given these possible drug interactions and other risks, it is always a good idea to check with your doctor before starting a new quercetin supplement.

Side Effects

Here are some of the side effects that are associated with quercetin supplements.

  • Headache
  • Stomachache
  • Impaired function of some proteins
  • Kidney damage (in doses greater than 1 gram per day)

Food Sources of Quercetin

Quercetin is considered one of the most widely available flavonoids in the Western diet.

 It’s generally recommended to get nutrients like quercetin from whole foods, rather than supplements, for optimal health — that’s because vitamins and minerals are most powerful when they come from food (where they’re accompanied by other helpful compounds).

 “By focusing on fruits, vegetables, and other healthy options, you can get a range of beneficial components — not just one particular nutrient,” says Wright.
You can find quercetin in a variety of healthy fruits, vegetables, and other plant sources. Here’s how much quercetin can be found in 100 grams (g) of the following foods.

  • Apples: 4.01 milligrams (mg)
  • Asparagus: 14 mg
  • Black tea: 2.5 mg
  • Blueberries: 14.6 mg
  • Broccoli: 13.7 mg
  • Cherries: 17.4 mg
  • Chili pepper: 32.6 mg
  • Fennel leaves: 46.8 mg
  • Kale: 22.6 mg
  • Lettuce: 14.7 mg
  • Onions: 45 mg
  • Oregano: 42 mg
  • Red wine: 3.16 mg

How to Select and Store Quercetin

If you decide to take quercetin supplements after speaking with your doctor, it’s important to choose a quality product and store it properly for maximum effect.

Selection

Look for supplements that have been tested for purity and potency by a reputable organization, such as USP, NSF, or ConsumerLabs. This testing ensures that the contents match the label.

Quercetin is sometimes combined with another nutrient. For example, supplements containing quercetin and vitamin D are marketed as being beneficial for physical performance. But research hasn’t found this combination to be effective for improving measures of fitness in adults with adequate vitamin D, testosterone, and antioxidant status.

Limited research suggests that combining quercetin with vitamin C may strengthen its antiviral properties, making it a potential tool for preventing respiratory infections like COVID-19 — though other studies have found no benefit.

Multi-nutrient supplements may be beneficial for people who aren’t getting adequate amounts of those nutrients in their diets. But if nutrient intake is sufficient through food, a quercetin-only supplement is usually preferable — unless your doctor recommends otherwise.

Storage

Store quercetin supplements according to the manufacturer’s instructions. This may involve storing them in a cool, dry place (like a cabinet away from sunlight).

Dosage of Quercetin

If your doctor thinks you might benefit from quercetin supplements, it’s important to talk to them about the dose they’d recommend you take. Typical doses based on research range from about 250 to 1,000 mg per day. Quercetin supplements are generally taken daily by mouth for up to 12 weeks at a time.

The Takeaway

  • Quercetin is an antioxidant that’s common in several plant foods and is being studied for its potential anti-inflammatory effects on the body.
  • Quercetin is being studied for its potential benefits for heart health, blood sugar management, and cancer prevention, but more high-quality research is needed.
  • Given the limited research for specific health concerns, it's best to get quercetin in the diet by eating more plant foods rather than taking it in supplement form.

FAQ

Who should (and should not) take quercetin?

You may consider taking quercetin supplements to potentially help reduce inflammation, manage blood sugar levels or protect against heart disease, if recommended by your doctor or registered dietitian. You should not take quercetin if you’re pregnant or breastfeeding, or if you have kidney problems. Overall the clinical research is limited though, especially for longer term use.

Coenzyme Q10 (CoQ10) is an antioxidant that may help complement treatments for heart disease, high cholesterol, and diabetes. Unlike quercetin, CoQ10 is found naturally in your body, though the amounts decrease with age. It’s also found in different food sources: mainly nuts, meats, and fish.

Quercetin has antioxidant effects, meaning that it may help neutralize free radicals and protect healthy cells from damage. Early lab and animal research suggests that quercetin may support your immune system by fighting inflammation and viruses, but more human studies are needed to confirm these effects.

Quercetin is primarily found in fruits and vegetables. Good sources of quercetin include red wine, green tea, onions, apples, and berries.

Taking quercetin daily in doses up to 1,000 mg may be safe for healthy adults, but only when used on a short-term basis of up to 12 weeks. In some cases, your doctor may recommend you take a quercetin supplement for longer if it's being used to treat a medical condition, and it's important to discuss the potential risks and benefits of this longer term use with them.

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