QUERCETIN

OTHER NAME(S):

3,3',4'5,7-Penthydroxyflavone, Bioflavonoid, Bioflavonoid Complex, Bioflavonoid Concentrate, Bioflavonoid Extract, Bioflavonoïde, Bioflavonoïde de Citron, Bioflavonoïdes de Citron, Citrus Bioflavones, Citrus Bioflavonoid, Citrus Bioflavonoids, Citrus Bioflavonoid Extract, Citrus Flavones, Citrus Flavonoids, Complexe de Bioflavonoïde, Concentré de Bioflavonoïde, Extrait de Bioflavonoïde, Extrait de Bioflavonoïdes de Citron, Flavones de Citron, Flavonoid, Flavonoïde, Meletin, Mélétine, Quercetina, Quercétine, Sophretin, Sophrétine.<br/><br/>

Overview

Overview Information

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. But there is limited scientific evidence to support these uses.

How does it work?

Quercetin has antioxidant and anti-inflammatory effects which might help reduce prostate inflammation.

Uses

Uses & Effectiveness?

Possibly Ineffective for

  • Exercise performance. Taking quercetin before exercise does not appear to improve fatigue, reduce muscle soreness, or decrease swelling.

Insufficient Evidence for

  • Heart disease. Some research suggests that eating foods rich in quercetin, such as tea, onions and apples, may reduce the risk of death due to heart disease in elderly men. However, taking a daily quercetin supplement does not seem to improve heart disease risk factors in people who are healthy.
  • Exercise-induced respiratory infections. Early research shows that taking quercetin may reduce the chance for upper respiratory infections after heavy exercise.
  • High cholesterol. Early research shows that short-term use of quercetin supplements does not lower “bad cholesterol” (low-density lipoprotein (LDL) cholesterol), lower total cholesterol, or raise “good cholesterol” (high-density lipoprotein (HDL) cholesterol).
  • High blood pressure. Early research suggests that taking quercetin aglycone produces a small (5-7 mmHg) decrease in blood pressure in people with untreated, mild high blood pressure. It’s not known yet how important this is.
  • Kidney transplantation. Some research suggests that taking a specific product containing a combination of 20 mg of quercetin and 480 mg of curcumin once or twice daily, starting within 24 hours of kidney transplantation and continuing for one month, in combination with anti-rejection drugs, improves early function of the transplanted kidney.
  • Lung cancer. Some research suggests that consuming high amounts of quercetin in the diet might reduce the chance of developing lung cancer, especially in men who smoke.
  • Ovarian cancer. One population study found no link between quercetin intake from the diet and the chance of ovarian cancer.
  • Pancreatic cancer. Some research suggests that eating high amounts of quercetin in the diet might reduce the chance of developing pancreatic cancer, especially in men who smoke.
  • Prostate pain and swelling (inflammation). Taking quercetin by mouth seems to reduce pain and improve quality of life, but doesn’t seem to help urination problems in men with ongoing prostate problems that aren’t due to infection.
  • Asthma.
  • Cancer.
  • Cataracts.
  • Chronic fatigue syndrome (CFS).
  • Diabetes.
  • Gout.
  • “Hardening of the arteries” (atherosclerosis).
  • Hay fever (allergic rhinitis).
  • Pain and swelling (inflammation).
  • Schizophrenia.
  • Stomach and intestinal ulcers.
  • Viral infections.
  • Other conditions.
More evidence is needed to rate quercetin for these uses.

Side Effects

Side Effects & Safety

Quercetin is POSSIBLY SAFE for most people when taken by mouth short-term. Quercetin has been safely used in amounts up to 500 mg twice daily for 12 weeks. It is not known if long-term use or higher doses are safe.

When taken by mouth, quercetin can cause headache and tingling of the arms and legs. Very high doses might cause kidney damage.

When given intravenously (by IV) in appropriate amounts (less than 722 mg), quercetin is POSSIBLY SAFE . Side effects may include flushing, sweating, nausea, vomiting, difficulty breathing, or pain at the injection site. But larger amounts given by IV are POSSIBLY UNSAFE . There have been reports of kidney damage at higher doses.

Special Precautions & Warnings:

Pregnancy and breast-feeding : Not enough is known about the use of quercetin during pregnancy and breast-feeding. Stay on the safe side and avoid use.

Interactions

Interactions?

Moderate Interaction

Be cautious with this combination

!
  • Antibiotics (Quinolone antibiotics) interacts with QUERCETIN

    Taking quercetin along with some antibiotics might decrease the effectiveness of some antibiotics. Some scientists think that quercetin might prevent some antibiotics from killing bacteria. But it's too soon to know if this is a big concern.<br><nb>Some of these antibiotics that might interact with quercetin include ciprofloxacin (Cipro), enoxacin (Penetrex), norfloxacin (Chibroxin, Noroxin), sparfloxacin (Zagam), trovafloxacin (Trovan), and grepafloxacin (Raxar).

  • Cyclosporin (Neoral, Sandimmune) interacts with QUERCETIN

    Cyclosporin (Neoral, Sandimmune) is changed and broken down by the liver. Quercetin might decrease how quickly the liver breaks down cyclosporin (Neoral, Sandimmune). Taking quercetin might increase the effects and side effects of this medication. Before taking quercetin talk to your healthcare provider if you take cyclosporin (Neoral, Sandimmune).

  • Medications changed by the liver (Cytochrome P450 2C8 (CYP2C8) substrates) interacts with QUERCETIN

    Some medications are changed and broken down by the liver. Quercetin might decrease how quickly the liver breaks down some medications. Taking quercetin along with these medications that are changed by the liver might increase the effects and side effects of your medication. Before taking quercetin talk to your healthcare provider if you take any medications that are changed by the liver.<br><nb>Some medications that are changed by the liver include paclitaxel (Taxol), rosiglitazone (Avandia), amiodarone (Cordarone), docetaxel (Taxotere), repaglinide (Prandin), verapamil (Calan, Isoptin, Verelan), and others.

  • Medications changed by the liver (Cytochrome P450 2C9 (CYP2C9) substrates) interacts with QUERCETIN

    Some medications are changed and broken down by the liver. Quercetin might decrease how quickly the liver breaks down some medications. Taking quercetin along with these medications that are changed by the liver might increase the effects and side effects of your medication. Before taking quercetin talk to your healthcare provider if you take any medications that are changed by the liver.<br><nb>Some medications that are changed by the liver include celecoxib (Celebrex), diclofenac (Voltaren), fluvastatin (Lescol), glipizide (Glucotrol), ibuprofen (Advil, Motrin), irbesartan (Avapro), losartan (Cozaar), phenytoin (Dilantin), piroxicam (Feldene), tamoxifen (Nolvadex), tolbutamide (Tolinase), torsemide (Demadex), warfarin (Coumadin), and others.

  • Medications changed by the liver (Cytochrome P450 2D6 (CYP2D6) substrates) interacts with QUERCETIN

    Some medications are changed and broken down by the liver. Quercetin might decrease how quickly the liver breaks down some medications. Taking quercetin along with these medications that are changed by the liver might increase the effects and side effects of your medication. Before taking quercetin talk to your healthcare provider if you take any medications that are changed by the liver.<br><nb>Some medications that are changed by the liver include amitriptyline (Elavil), codeine, flecainide (Tambocor), haloperidol (Haldol), imipramine (Tofranil), metoprolol (Lopressor, Toprol XL), ondansetron (Zofran), paroxetine (Paxil), risperidone (Risperdal), tramadol (Ultram), venlafaxine (Effexor), and others.

  • Medications changed by the liver (Cytochrome P450 3A4 (CYP3A4) substrates) interacts with QUERCETIN

    Some medications are changed and broken down by the liver. Quercetin might decrease how quickly the liver breaks down some medications. Taking quercetin along with these medications that are changed by the liver might increase the effects and side effects of your medication. Before taking quercetin talk to your healthcare provider if you take any medications that are changed by the liver.<br><nb>Some medications that are changed by the liver include lovastatin (Mevacor), clarithromycin (Biaxin), cyclosporine (Neoral, Sandimmune), diltiazem (Cardizem), estrogens, indinavir (Crixivan), triazolam (Halcion), verapamil (Calan, Isoptin, Verelan), alfentanil (Alfenta), fentanyl (Sublimaze), losartan (Cozaar), fluoxetine (Prozac), midazolam (Versed), omeprazole (Prilosec), lansoprazole (Prevacid), ondansetron (Zofran), propranolol (Inderal), fexofenadine (Allegra), amitriptyline (Elavil), amiodarone (Cordarone), citalopram (Celexa), sertraline (Zoloft), ketoconazole (Nizoral), itraconazole (Sporanox), and numerous others.

  • Medications moved by pumps in cells (P-glycoprotein Substrates)) interacts with QUERCETIN

    Some medications are moved by pumps in cells. Quercetin might make these pumps less active and increase how much of some medications get absorbed by the body. This might cause more side effects from some medications.<br><nb>Some medications that are moved by these pumps include diltiazem (Cardizem), verapamil (Calan, Isoptin, Verelan), digoxin (Lanoxin) cyclosporine (Neoral, Sandimmune), saquinavir (Invirase), amprenavir (Agenerase), nelfinavir (Viracept), loperamide (Imodium), quinidine, paclitaxel (Taxol), vincristine, etoposide (VP16, VePesid), cimetidine (Tagamet), ranitidine (Zantac), fexofenadine (Allegra), ketoconazole (Nizoral), itraconazole (Sporanox), and others.

Dosing

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.

View References

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CONDITIONS OF USE AND IMPORTANT INFORMATION: This information is meant to supplement, not replace advice from your doctor or healthcare provider and is not meant to cover all possible uses, precautions, interactions or adverse effects. This information may not fit your specific health circumstances. Never delay or disregard seeking professional medical advice from your doctor or other qualified health care provider because of something you have read on WebMD. You should always speak with your doctor or health care professional before you start, stop, or change any prescribed part of your health care plan or treatment and to determine what course of therapy is right for you.

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