Reviews and Information for Quercetin
Quercetin & Rutin Supplements
Quercetin has been touted for many uses including allergy, viral infection, and more. But what is the evidence and which quercetin supplements are best? ConsumerLab reviewed the research and purchased and tested the quality of popular quercetin and rutin supplements, coming up with some big surprises.
Quercetin & Rutin Supplements Review
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CL Answer
Is quercetin helpful for a specific condition? I see it as an ingredient in several different types of supplements.
Learn more about quercetin, including the benefits of quercetin and other evidence from clinical studies on prostatitis and memory.
Product Review
Resveratrol Supplements Review (From Red Wine, Knotweed, and Other Sources)
See Which Resveratrol Supplements Were Best In Our Tests and Comparisons. Learn What Resveratrol Can and Can't Do.
Product Review
Ginkgo (Ginkgo Biloba) Supplements Review
Choose the Best Ginkgo Biloba Supplement. Finding Real Ginkgo Isn't Easy — 60% Fail ConsumerLab's Tests of Quality.
CL Answer
Does Z-Stack multivitamin work to boost the immune system, and is it safe?
Find out about Z-Stack, including if it can help boost the immune system and if it is safe to use at the suggested dose.
News Release
February 26, 2024
Latest ConsumerLab Survey Shows Growth in Popularity of Magnesium and Several Smaller Supplements
White Plains, New York, February 26, 2024 — A recent survey of more than 10,000 people who regularly use dietary supplements shows that supplements that experienced the greatest absolute growth in popularity during 2023 were pregnenolone (+7.5 percentage points), magnesium (+4.8 pts), berberine (+4.
News Release
March 30, 2023
ConsumerLab Tests Show Not All Quercetin and Rutin Supplements Contain What They Claim
White Plains, New York, March 30, 2023 — Quercetin is a plant compound found in its natural form, rutin, in foods such as capers, onions, and kale.
CL Answer
Do any supplements help with COVID-19? Do supplements like vitamin D, zinc, vitamin C, or herbals work?
Find out if natural remedies & supplements for coronavirus such as zinc, vitamin C, garlic, or elderberry help to prevent or treat COVID-19.
Product Review
Multivitamin and Multimineral Supplements Review
Best Multivitamins In 2023 -- Caution with Gummies
Product Review
Prostate Supplements Review (Saw Palmetto and Beta-Sitosterol)
Find the Best Prostate Supplement for Symptoms of BPH. See Which Prostate Supplement Passed or Failed CL's Tests of Quality.
CL Answer
Which supplements are best for seasonal allergies?
Find out which supplements are best for allergies and can help reduce seasonal allergy symptoms, including bromelain, curcumin, vitamin D, and CLA.
Clinical Update
3/31/2023
Quercetin and Antivirals
Be aware that quercetin might reduce the effectiveness of some antivirals, including an antiviral in Paxlovid used to treat COVID-19. Get the details in the Concerns and Cautions section of our Quercetin Supplements Review, which includes information about other potential interactions with quercetin, as well as our Top Picks among quercetin supplements.
Also see our CL Answer about Supplements for COVID-19.
Clinical Update
12/19/2023
Caution With Quercetin and Heart Medication
Quercetin may interact with many medications, including one for irregular heart rhythm, according to preliminary research. See medications with which quercetin may interact in the Concerns and Cautions section of our Quercetin Supplements Review. Also see our Top Picks among quercetin supplements.
CL Answer
Are there supplements that can reduce prostate size?
How to reduce prostate size using supplements for benign prostatic hyperplasia (BPH), including beta-sitosterol and saw palmetto.
Clinical Update
3/31/2020
Is Quercetin Safe?
Quercetin has been proposed as a treatment for a range of medical conditions, including COVID-19, but is it safe? Find out what studies have found, including results of a recent, small clinical trial, in the Concerns and Cautions section of the Quercetin Supplements Review. Also see our Top Picks for quercetin.
Clinical Update
11/05/2021
Quercetin & COVID
Find out if quercetin helped people with early-stage COVID-19 in a recent study. Details are in the Viral Infections section of our Quercetin Supplements Review, which includes our test results and Top Picks among quercetin supplements.
Clinical Update
11/23/2023
Headache, Alcohol, and Quercetin
Quercetin may put one at risk for headache and facial flushing when drinking alcohol, according to recent research. Quercetin is also known to interact with many prescription drugs. See the details in the Concerns and Cautions section of our Quercetin and Rutin Supplements Review.
Clinical Update
5/13/2022
Most Quercetin Brands Fail Test
Twenty out of 24 brands of quercetin purchased on Amazon contained much less quercetin than listed in a recent analysis. For details by brand, see the Quality Concerns section of our Quercetin Review.
Clinical Update
12/07/2021
Quercetin for Severe COVID?
Does quercetin help people with severe COVID-19? See what a recent study suggests in the Viral Infections section of our Quercetin Supplements Review. Also see our Top Picks for quercetin.
Clinical Update
7/22/2024
Quercetin for Fatty Liver?
Can taking quercetin reduce liver fat in people with fatty liver disease? Find out what a recent study showed in the What It Does section of our Quercetin Supplements Review, which includes our Top Picks for quercetin.
Also see: Do any supplements help with fatty liver disease? Are some diets more beneficial than others?
CL Answer
Which supplements may help with PCOS (polycystic ovarian syndrome)?
Many supplements are promoted to help treat symptoms of PCOS (polycystic ovarian syndrome), but do they really work? See the clinical evidence for inositol (myo-inositol and D-chiro-inositol), alpha lipoic acid, vitamin B-12, folic acid, vitamin D and more.
Product Review
Fruits, Veggies, and Other Greens Supplements Review (Including Spirulina and Chlorella)
Avoid Lead in Greens, Problems with Pills, and Don't Give Up Eating Whole Foods.
Clinical Update
6/01/2022
Quercetin From Food or Supplements?
Is it more cost effective to get quercetin from food (as rutin) than supplements? See our answer in the Quercetin Review.
Clinical Update
7/19/2022
Quercetin for Seasonal Allergies?
Did quercetin improve nasal and eye symptoms among people with seasonal allergies in recent study? Find out in the Seasonal Allergy section of our Quercetin Supplements Review.
CL Answer
Dietary Supplements and Herbs to Avoid When Breastfeeding
Find out which supplements should be avoided when breastfeeding, including medicinal herbs, soy, and flaxseed.
CL Answer
Are supplements such as Thyroid Care Plus helpful for hypothyroidism? Can supplements worsen thyroid function? And what is nascent iodine?
Learn about supplement ingredients such as iodine, selenium, zinc, acetyl-l-carnitine, ashwagandha and guggul used for thyroid conditions and find out if they are beneficial. Also learn why ingredients such as alpha-lipoic acid, soy, resveratrol, quercetin may impair thyroid function.
CL Answer
What are the health benefits of tart cherry juice?
See the evidence for tart cherry juice health benefits from clinical studies. Find out if tart cherry has anti-inflammatory effects, if it can improve sleep, lower high blood pressure, or help for muscle pain and osteoarthritis.
CL Answer
I take warfarin (Coumadin), an anticoagulant drug. Are there supplements I should avoid, or be taking, due to this drug?
Find out which supplements should be avoided when taking blood thinners (anticoagulants) like warfarin (Coumadin), including vitamin K, St. John's wort, and curcumin.
CL Answer
What are the health benefits of luteolin, and is it safe?
Find out if luteolin, a compound found in many fruits and vegetables, is beneficial for cancer, heart health, skin aging, age-related cognitive decline, and other conditions, and learn if it's safe.
CL Answer
I've heard that grapefruit juice can interact with medications because it inhibits an enzyme that breaks down drugs in the body. Do any supplements interact the same way with drugs?
CYP3A4 inhibitors, such as grapefruit, can interact with certain medications by inhibiting the liver enzyme that metabolizes many drugs. ConsumerLab.com's answer explains.
CL Answer
Do diamine oxidase (DAO) supplements for histamine intolerance really work?
DAO supplement info for histamine intolerance, including diamine oxidase safety, evidence from clinical studies, and dosage.
CL Answer
Are there supplements that interact with estrogen-replacement therapies like Premarin and Estrace?
Estrogen hormone replacement therapy pills, creams, and tablets, such as Premarin, Estrace, Imvexxy, Ogen, and Vagifem can interact with certain supplements and foods, including St. John's wort and grapefruit juice. Learn more.
Product Review
Joint Health Supplements Review (Glucosamine, Chondroitin, MSM, Boswellia, Collagen and Turmeric)
One-Third of Joint Health Supplements Failed to Pass Our Tests. See Which Passed or Failed, and our Top Picks.
CL Answer
Is it true that NAC can help clear nasal passages?
Find out if N-Acetyl Cysteine (NAC) can help with post nasal drip & general sinus congestion and about supplements that may reduce cold symptoms.
CL Answer
Which supplements can help treat anemia? Do any supplements cause a low red blood cell count?
Find out which vitamin and nutrient supplements can help prevent and treat anemia in people who are nutrient deficient and learn which supplements may cause low blood cell counts, especially when used in excess.
CL Answer
Does Rooibos Tea Have Health Benefits and Is It Safe?
Learn about the health benefits of rooibos tea, including red and green, unfermented rooibos tea, how is differs from black and green tea, safety, and potential drug interactions with rooibos tea.
CL Answer
Mullein Tea: Possible Health Effects and Safety
Mullein tea is often promoted for relieving symptoms of lung conditions, including coughing, hoarseness, sore throat, and shortness of breath. Find out if there is evidence to support these uses, and learn about possible side effects of mullein.
CL Answer
What is graviola? Can it really help fight cancer?
Learn more about graviola, if it can really help fight cancer, and its safety.
CL Answer
Are there supplements I should avoid when taking apixaban (Eliquis) or similar blood thinner drugs like Xarelto?
Learn about supplement interactions with apixaban (Eliquis), rivaroxaban (Xarelto) and other blood thinner drugs in the direct factor Xa inhibitors class.
CL Answer
When taking a statin drug like Lipitor or Crestor, are there supplements I should avoid or take?
Learn about the interactions between certain supplements and atorvastatin (Lipitor), rosuvastatin (Crestor), and other cholesterol-lowering statins.
CL Answer
10 Supplements That May Boost Testosterone (And 13 That May Not)
Many supplements promise to increase testestorone, boost libido, and increase muscle size, but, as ConsumerLab explains, the actual effectiveness of supplements is limited, and some supplements may actually reduce testosterone levels.
Product Review
Elderberry Supplements Review
Find the Best Elderberry Supplement. Tests and Reviews of Popular Elderberry Supplements & CL's Top Picks.
CL Answer
Which supplements and foods help with gout and which may worsen it?
Find out about the effects on uric acid levels and gout of fish and fish oil, coffee, beer, animal meat, milk proteins, vegetable proteins, fructose, lemon juice, tart cherry juice, vitamin A, vitamin C, and niacin
CL Answer
Are supplements which claim increased absorption or improved bioavailability telling the truth? Is it worth paying more for these? Are there concerns?
Learn more about bioavailability enhancers, including emulsifiers and enzyme inhibitors.
CL Answer
Do hair loss supplements, such as Viviscal, Hair La Vie, and Nutrafol, or topical essential oils work?
Vitamins and supplements that may help with hair loss and thinning, including saw palmetto, beta-sitosterol, protein, iron, and vitamin D.
Product Review
Vitamin C Supplements Review
Find the Best Vitamin C Supplements
Recalls & Warnings
December 09, 2021
FDA Warns Seller of Curcumin, Lion's Mane, Quercetin & More
On November 9, 2021, the FDA issued a warning letter to Synaptent, LLC because it found statements on the company's website about its products, including Berberine HCL, Curcumin, Lion's Man, Milk Thistle, Quercetin, Boswellia Serrata Extract, and Garlic Extract to be ...
CL Answer
Do any supplements help with fatty liver disease? Are some diets more beneficial than others?
Find out if supplements such as vitamin E, fish oil, milk thistle, curcumin, choline, probiotics, vitamin D, reishi mushroom, or extra virgin olive oil are beneficial for fatty liver disease and learn which diet (Mediterranean, ketogenic, DASH, or fasting diets) seems to have greatest benefit.
CL Answer
Risks of Too Many Vitamins & Supplements
Taking too many vitamin supplements -- or taking too much of a particular supplement -- can have short and long-term adverse effects.
CL Answer
Do any supplements help for varicose veins or chronic venous insufficiency?
Find out which supplements help for varicose veins and chronic venous insufficiency, including citrus bioflavonoids and grape seed extract.
News Release
February 24, 2023
Probiotics Rise in Popularity as Vitamin C, Melatonin, and Others Dip in Latest ConsumerLab Survey of Supplement Users
White Plains, New York, February 25, 2023 —A recent survey of 8,600 people who regularly use dietary supplements shows that probiotics (+3.04 percentage points), quercetin (+2.3 pts), and vitamin K (+1.
Recalls & Warnings
December 11, 2020
FDA Warns iThrive.health for Promoting Supplements as COVID-19 Treatments
On December 10, 2020, the FDA issued a warning letter to iThrive.health for promoting the sale of various vitamins and supplements on Amazon.com with claims that they can mitigate, prevent, treat, diagnose, or cure COVID-19.
CL Answer
Do any supplements help prevent or treat a cold?
Are there supplements that can help prevent or treat cold symptoms? Learn more about zinc, probiotics, vitamin C and more.
CL Answer
Which vitamins and minerals should be taken together or separately?
Find out the best way to take vitamins and minerals and which vitamins and minerals should be taken together or separately for proper absorption. ConsumerLab answer explains the best way to take vitamins and minerals.
CL Answer
I take omeprazole (Prilosec), a proton pump inhibitor, to reduce stomach acid. Are there supplements I should avoid, or be taking, due to this drug?
Supplement interactions with proton pump inhibitor (PPI) drugs like omeprazole (Prilosec) and Nexium.
Recalls & Warnings
December 01, 2022
FTC Takes Action Against Company Promoting “COVID Resist” Supplement to Treat COVID-19
On November 22, 2022, the FTC filed a complaint in a U.S. district court against California-based company Precision Patient Outcomes, Inc. for promoting its COVID Resist and VIRUS Resist supplements to prevent and treat COVID-19.
Recalls & Warnings
October 05, 2023
Counterfeit Pure Encapsulations and GutConnect 365 Sold on Amazon
On September 26, 2023, a man from New Jersey was arrested for selling fake versions of Pure Encapsulations L-Glutamine and Nature MD's GutConnect 365 on Amazon.
News Release
February 24, 2022
Consumers Returned to Pre-Pandemic Supplement Usage in 2021, ConsumerLab Survey Reveals
White Plains, New York, February 24, 2022 —A survey of 8,049 people who use dietary supplements shows many supplements that declined in use in 2020 began bouncing back in 2021, such as magnesium (+2.4 percentage points), and CoQ10 (+2.7 pts).
Recalls & Warnings
January 03, 2022
Seller of Wormwood, Aloe Supplement Warned by FDA
On December 7, 2021, the FDA issued a warning letter for Western Herb Products, Inc.
News Release
February 26, 2021
COVID Changed Supplement Popularity in 2020, ConsumerLab Survey Reveals
White Plains, New York, February 26, 2021 — A survey of 9,647 people who use dietary supplements shows that the supplements which experienced the greatest growth in popularity in 2020 were those being promoted to prevent or treat infection with SARS-CoV-2, the coronavirus that causes COVID-19.
Recalls & Warnings
June 02, 2022
Walmart Inc. Recalls Joint Supplements With Omega-3, Glucosamine & Curcumin
On May 28, 2022, Walmart Inc. issued a voluntary recall of all lots of Artri Ajo King Joint Supplements after FDA laboratory analysis found the presence of undeclared diclofenac.
Recalls & Warnings
September 28, 2022
FDA Warns Muscle Sports for Joint Health, Immune & Workout Supplement, Vitamin C, Elderberry, and Other Claims
On September 23, 2022, the FDA issued a warning letter to Muscle Sports Products, LLC following inspection of the company’s websites which found statements about company products, including Join Revolution Capsules, IMMUNITY + Powder, Rhino Rampage PUMPED Capsules, Attack Pre-Workout ...
Recalls & Warnings
December 22, 2021
FDA Warns Seller of Liquid Magnesium, B-12, Berberine & More
On December 9, 2021, the FDA issued a warning letter to Wholly Liquid Nutritional Supplements LLC because it found statements on the company's website and social media about its products, including SpiroLaze, BioLaze, LiquiLaurin, VIT-B12, DeStress, and Omega Plus, to be ...
CL Answer
10 Supplements That May Help Reduce Nighttime Urination (And 5 That May Not)
Waking up more than once during the night to use the bathroom? Learn more about the 9 supplements that may help and 5 others that don't.
News Release
January 16, 2021
Best Resveratrol Products Revealed in ConsumerLab Review
White Plains, New York, January 16, 2021 — Resveratrol supplements are promoted for a wide range of uses, including lowering cholesterol and improving cardiovascular health, improving memory, reducing inflammation and slowing age-related macular degeneration.
News Release
June 06, 2020
Best Vitamin C Supplements Revealed by ConsumerLab
White Plains, New York, June 6, 2020 — Due to its role in maintaining immune system health, vitamin C has been promoted to help prevent and treat COVID-19, as well as other viral infections such as colds.
Recalls & Warnings
June 20, 2020
FTC Warns 30 More Companies for Coronavirus Claims
On June 18, 2020, the FTC announced that it sent warning letters to 30 companies for selling products such as immune system boosters, colloidal silver, vitamin C, and CBD with unsupported claims that they can treat coronavirus (COVID-19).
Recalls & Warnings
May 23, 2020
FTC Warns 50 More Companies for Coronavirus Claims
On May 21, 2020, the FTC announced that it sent warning letters to 50 companies for selling products such as herbal products, immune system boosters, and vitamin C, with unsupported claims that they can treat coronavirus (COVID-19).
Recalls & Warnings
May 09, 2020
FTC Warns 45 More Companies for Coronavirus Claims
On May 7, 2020, the FTC announced that it sent warning letters to 45 companies for selling products such as herbal products, immune system boosters, and vitamin C with unsupported claims that they can treat coronavirus (COVID-19).
Recalls & Warnings
September 05, 2014
Seller of "Nerve", "Cleanse" and Probiotic Supplements Warned for Drug Claims
On July 30, 2014, the FDA issued a warning letter to Plexus Worldwide, Inc., following a review of the company's website and product labels, which found statements made about Fast Relief, BioCleanse and ProBio5 to be drug claims.
News Release
April 01, 2019
Not All Quercetin Supplements Contain What They Claim, ConsumerLab Tests Reveal
White Plains, New York, April 1, 2019 — Quercetin is a flavonoid found in foods such as onions, kale and apples. Sold as a supplement, quercetin is promoted to help with a range of conditions including prostatitis, asthma, and rheumatoid arthritis, as well as blood sugar control.
News Release
January 29, 2014
You May Be Getting More Vitamin C Than You Think from Some Supplements, Cautions ConsumerLab.com -- 27% of Vitamin C Supplements Don't Meet Label Claims in Recent Tests --
White Plains, New York, January 29, 2014 — It's cold and flu season, which means many people are reaching for vitamin C, as it may modestly reduce cold symptoms (although it won't prevent a cold).
News Release
March 12, 2012
Review of vitamin C supplements by ConsumerLab.com finds many of high quality but a wide range in prices
White Plains, New York — March 8, 2012 — Vitamin C may boost the immune system and is critical for maintaining healthy connective tissue, but do you need to take a supplement and, if so, how do you find one that is right for you and at the best price? ConsumerLab.
Recalls & Warnings
December 05, 2014
Maker of Ginseng, Zinc, Calcium and More Warned for Manufacturing Violations
On November 20, 2014, the FDA issued a warning letter to Long Island Pharmaceuticals, LLC, following a facility inspection which found the company's products to be adulterated because they were prepared, packed, or held under conditions that violate Current Good Manufacturing Practices for dietary ...
Recalls & Warnings
April 18, 2013
Cardio, Energy and Sexual Enhancement Supplement Distributor Warned For Manufacturing Violations and Drug Claims
On December 21, 2012, the FDA issued a warning letter to ForMor Inc, dba ForMor International, following a facility inspection which found the company's Cardio Cocktail and Argenix dietary supplements to be adulterated because because they were prepared, packed, or held under conditions that do ...
Recalls & Warnings
November 21, 2012
Maker of Blood Pressure, Probiotic, Resveratrol and Hormonal Supplements Warned For Manufacturing Violations and Drug Claims
On November 2, 2012, the FDA issued a warning letter to Atrium, Inc. following a facility inspection which found a number of the company's dietary supplements to be adulterated or promoted as drugs.
Recalls & Warnings
November 02, 2012
Manufacturer of Prostate, Inflammation and Cholesterol Supplements Warned For Drug Claims
On October 15, 2012, the FDA issued a warning letter to Ortho Molecular Products, Inc. for making drug claims about the following dietary supplements: Candicid Forte, Inflamma-bLOX, Lipitrol, Mucosagen, Prostatrol Forte, Resvoxitrol, Paracid Forte, VascuPak HTN and Lithium Orotate.
Recalls & Warnings
February 13, 2013
Manufacturer of Heart, Multivitamin, Cranberry, and Longevity Supplements Warned For Adulteration and Drug Claims
On January 29, 2013, the FDA issued a warning letter to M.D.R. Fitness Corp. following a facility inspection which found violations of good manufacturing practices which cause the company's products to be adulterated.
Recalls & Warnings
April 26, 2013
Seller of Immune, Cholesterol, Liver and Blood Sugar Products Warned For Drug Claims
On March 20, 2013, the FDA issued a warning letter to Birkdale Medicinals LLC, following a review of the company's website which found statements made about Birkdale products, including Immune Response 247, Cholestat, Silymarin 81 and LevelStat, to be drug claims.
Recalls & Warnings
November 06, 2014
Seller of Prostate, Heart Supplements and More Warned for Drug Claims
On October 9, 2014, the FDA issued a warning letter to Health Research Laboratories, LLC/New World Health, following a review of the company's websites, which found statements made about AtheChel Advanced, Betarol, BioTherapex, Omega-3 Cardio Plus, RejuvaLifeRx, and Ultimate Health Formula to be ...
Recalls & Warnings
July 25, 2013
Beware of Dietary Supplements With Claims To Treat Diabetes, FDA Warns
On July 23, 2013, the FDA issued a warning to consumers not to buy or use dietary supplements that are promoted to treat diabetes.
