Quercetin

Botanicals

18/Description

About

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 used for treating conditions of the heart and blood vessels including “hardening of the arteries” (atherosclerosis), high cholesterol, heart disease, and circulation problems. It is also used for diabetes, cataracts, hay fever, peptic ulcer, schizophrenia, inflammation, asthma, gout, viral infections, chronic fatigue syndrome (CFS), preventing cancer, and for treating chronic infections of the prostate. Quercetin is also used to increase endurance and improve athletic performance.

How it works

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

Effectiveness

Possibly Effective
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.

Concerns

Possibly safe

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 longer-term use or larger amounts are safe.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

Possibly unsafe

But larger amounts given by IV are POSSIBLY UNSAFE. There have been reports of kidney damage at higher doses.

18/Warnings

Warnings

Pregnancy and breast-feeding: Not enough is known about the use of quercetin duringpregnancyandbreast-feeding. Stay on the safe side and avoid use.Are there any interactions with medications?

Interactions

Always consult with your doctor.
Moderate
Cyclosporine (Neoral, Sandimmune)

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.Quinolone antibiotics include ciprofloxacin (Cipro), levofloxacin (Levaquin), ofloxacin (Floxin), moxifloxacin (Avelox), gatifloxacin (Tequin), and others.A small study in healthy volunteers shows that giving quercetin before cyclosporine increases blood levels of the cyclosporine and lengthens the time it remains in the body.

Warfarin (Coumadin)

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 some medications that are broken down by the liver can increase the effects and side effects of these medications. Before taking quercetin, talk with your healthcare provider if you take any medications that are changed by the liver.Some medications that are changed by the liver include paclitaxel (Taxol), rosiglitazone (Avandia), amiodarone (Cordarone), docetaxel (Taxotere), tretinoins, repaglinide (Prandin), verapamil (Calan, Isoptin, Verelan, etc.), and others.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 some medications that are broken down by the liver can increase the effects and side effects of these medications. Before taking quercetin, talk with your healthcare provider if you take any medications that are changed by the liver.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), and warfarin (Coumadin).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 some medications that are broken down by the liver can increase the effects and side effects of these medications. Before taking quercetin, talk with your healthcare provider if you take any medications that are changed by the liver.Some drugs 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.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 some medications that are broken down by the liver can increase the effects and side effects of these medications. Before taking quercetin, talk with your healthcare provider if you take any medications that are changed by the liver.Some drugs that are changed by the liver include calcium channel blockers (diltiazem, nicardipine, verapamil), chemotherapeutic agents (etoposide, paclitaxel, vinblastine, vincristine, vindesine), antifungals (ketoconazole, itraconazole), glucocorticoids, 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), and numerous others.Quercetin seems to decrease blood pressure. Taking quercetin along with medications for high blood pressure might cause your blood pressure to go too low.Some medications for high blood pressure include captopril (Capoten), enalapril (Vasotec), losartan (Cozaar), valsartan (Diovan), diltiazem (Cardizem), Amlodipine (Norvasc), hydrochlorothiazide (HydroDIURIL), furosemide (Lasix), and many others.Quercetin might affect the way certain medications are processed by the body. Quercetin might make these medications easier for the body to use and make them last longer in the body.Some of the drugs that may be affected in these ways by quercetin include paclitaxel, diltiazem, cyclosporine, saquinavir, digoxin, cancer drugs (etoposide, vinblastine, vincristine, vindesine), antifungals (ketoconazole, itraconazole), protease inhibitors (amprenavir, indinavir, nelfinavir), H2 antagonists (cimetidine, ranitidine), verapamil, corticosteroids, erythromycin, fexofenadine (Allegra), loperamide (Imodium), quinidine, and others.A small test tube study shows that quercetin might increase the effects that warfarin has on the body. Taking quercetin and warfarin together might increase the chance of side effects of warfarin such as bruising and bleeding.

The information provided on this page is for reference purposes and is not meant to be used as a medical advice, diagnosis or treatment. Always consult with a medical professional. The content on this page has been provided with thanks by RxList.com