3,3',4'5,7-Pentahydroxyflavone, 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 InformationQuercetin 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.
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.
Uses & Effectiveness
Possibly Ineffective for
- Athletic performance. Most clinical research shows that taking quercetin before exercise does not decrease fatigue or improve exercise ability.
Insufficient Evidence for
- Autism. Early research shows that taking a product containing quercetin and other ingredients might improve behavior and social interactions in children with autism.
- Enlarged prostate (benign prostatic hyperplasia or BPH). Early research shows that taking a product containing quercetin, beta-sitosterol, and saw palmetto doesn't help with urination and other symptoms in men with BPH.
- 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.
- Diabetes. Early research shows that taking a combination of quercetin, myricetin, and chlorogenic acid helps to lower blood sugar in people with diabetes who are not taking antidiabetes drugs. Taking the same combination also seems to benefit people with diabetes who are already taking metformin.
- Muscle damage caused by exercise. Taking quercetin doesn't seem to help to prevent muscle soreness due to cycling or running. But it might prevent muscle damage associated with certain types of weight training.
- Airway infections caused by exercise. Early research shows that taking quercetin may reduce the chance for upper respiratory infections after heavy exercise.
- High cholesterol. Short-term use of quercetin does not appear to lower "bad cholesterol" (low-density lipoprotein (LDL) cholesterol) or total cholesterol, or to raise "good cholesterol" (high-density lipoprotein (HDL) cholesterol). But most of the studies conducted have been small and included people without high cholesterol. It's unclear if quercetin would show benefit in only people with high cholesterol.
- High blood pressure. Early research suggests that taking quercetin produces a small decrease in blood pressure in people with untreated, mild high blood pressure. It's unclear if this reduction in blood pressure is clinically meaningful.
- Kidney transplant. Some research suggests that taking a product containing quercetin and curcumin, starting within 24 hours of kidney transplantation, improves early function of the transplanted kidney when taken in combination with anti-rejection drugs.
- Lung cancer. Higher intake of quercetin as part of the diet has been linked with a lower risk of lung cancer in people who smoke.
- Swelling (inflammation) and sores inside the mouth (oral mucositis). Early research suggests that taking quercetin does not prevent mouth sores caused by cancer drugs.
- 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.
- A hormonal disorder that causes enlarged ovaries with cysts (polycystic ovary syndrome or PCOS). Research shows that taking quercetin improves hormone levels in women with PCOS by a small amount. In some people it might also improve how sensitive the body is to insulin. But it's unclear if these changes lead to improvements in symptoms of PCOS such as irregular periods.
- Swelling (inflammation) of the prostate due to infection. 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.
- Rheumatoid arthritis (RA). Research shows that taking quercetin reduces pain and stiffness in women with RA. But it doesn't seem to reduce the number of swollen or tender joints.
- Painful urination due to swelling (inflammation) of the urethra (urethral syndrome). Early research shows that taking a product containing quercetin, bromelain, chondroitin sulfate, gotu kola, rhodiola, and barbed skullcap helps reduce how often people with urethral syndrome need to urinate.
- Infections of the kidney, bladder, or urethra (urinary tract infections or UTIs). Early research suggests that taking a combination of hyaluronic acid, chondroitin sulfate, curcumin, and quercetin by mouth, and applying estrogen to the vagina, helps to prevent UTIs in women who get them often. The quercetin product also works without the estrogen, but not as well.
- Chronic fatigue syndrome (CFS).
- "Hardening of the arteries" (atherosclerosis).
- Hay fever (allergic rhinitis).
- Pain and swelling (inflammation).
- Stomach and intestinal ulcers.
- Viral infections.
- Other conditions.
Side Effects & SafetyWhen taken by mouth: 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 by IV: Quercetin is POSSIBLY SAFE when given intravenously (by IV) in appropriate amounts (less than 722 mg). 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 : There isn't enough reliable information to know if quercetin is safe to use when pregnant or breast-feeding. Stay on the safe side and avoid use.
Kidney problems : Quercetin might make kidney problems worse. Don't use quercetin if you have kidney problems.
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.
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.
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