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Quercetin is a plant pigment (flavonoid). It's found in many plants and foods, such as red wine, onions, green tea, apples, and berries.
Quercetin has antioxidant and anti-inflammatory effects that might help reduce swelling, kill cancer cells, control blood sugar, and help prevent heart disease.
Quercetin is most commonly used for conditions of the heart and blood vessels and to prevent cancer. It is also used for arthritis, bladder infections, and diabetes, but there is no strong scientific evidence to support most of these uses. There is also no good evidence to support using quercetin for COVID-19.
- Athletic performance. Oral quercetin does not seem to improve athletic performance.
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- Allergic rhinitis (hay fever). Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear.
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- Asthma. It is unclear if oral quercetin in beneficial in patients with asthma.
Login for details - Atherosclerosis. Login for details
- Autism spectrum disorder. Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear.
Login for details - Benign prostatic hyperplasia (BPH). Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear.
Login for details - Beta-thalassemia. It is unclear if oral quercetin in beneficial in patients with beta-thalassemia.
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- Canker sores. Topical quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear.
Login for details - Cardiovascular disease (CVD). It is unclear if oral quercetin in beneficial for CVD prevention.
Login for details - Cataracts. Login for details
- Chronic fatigue syndrome (CFS). Login for details
- Chronic venous insufficiency (CVI). Login for details
- Colorectal cancer. Login for details
- Contrast induced nephropathy. It is unclear if oral quercetin in beneficial for the prevention of contrast induced nephropathy.
Login for details - Coronavirus disease 2019 (COVID-19). Small, open-label clinical studies suggest that oral quercetin may modestly improve symptoms and prevent hospitalization in adults when taken in the early stages of COVID-19 infection.
Login for details - Diabetes. Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear.
Login for details - Exercise-induced muscle damage. It is unclear if oral quercetin in beneficial for preventing muscle damage associated with exercise.
Login for details - Exercise-induced respiratory infections. It is unclear if oral quercetin in beneficial for prevention of respiratory infections induced by exercise.
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- Herpes labialis (cold sores). Login for details
- Hypercholesterolemia. It is unclear if oral quercetin in beneficial for improving cholesterol levels.
Login for details - Hypertension. It is unclear if oral quercetin in beneficial for reducing blood pressure.
Login for details - Kidney transplant. Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear.
Login for details - Lung cancer. It is unclear if oral quercetin in beneficial in lung cancer prevention.
Login for details - Metabolic syndrome. It is unclear if oral quercetin in beneficial in patients with metabolic syndrome.
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- Obesity. Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear.
Login for details - Oral mucositis. It is unclear if oral quercetin in beneficial in patients with oral mucositis.
Login for details - Ovarian cancer. It is unclear if oral quercetin in beneficial for ovarian cancer prevention.
Login for details - Pancreatic cancer. It is unclear if oral quercetin in beneficial for pancreatic cancer prevention.
Login for details - Peptic ulcers. Login for details
- Polycystic ovary syndrome (PCOS). It is unclear if oral quercetin in beneficial in patients with PCOS.
Login for details - Prostatitis. It is unclear if oral quercetin in beneficial in patients with prostatitis.
Login for details - Rheumatoid arthritis (RA). It is unclear if oral quercetin in beneficial in patients with RA.
Login for details - Schizophrenia. Login for details
- Upper respiratory tract infection (URTI). Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear.
Login for details - Urethral syndrome. Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear.
Login for details - Urinary tract infections (UTIs). Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear.
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When taken by mouth: Quercetin is possibly safe for most people when used short-term. Quercetin has been safely used in doses up to 1 gram daily for 12 weeks. It's not known if long-term use or higher doses are safe.
When applied to the skin: There isn't enough reliable information to know if quercetin is safe or what the side effects might be.
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.
Antibiotics (Quinolone antibiotics)
Interaction Rating=Moderate Be cautious with this combination.
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.
Cyclosporin (Neoral, Sandimmune)
Interaction Rating=Moderate Be cautious with this combination.
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)
Interaction Rating=Moderate Be cautious with this combination.
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.
Medications changed by the liver (Cytochrome P450 2C9 (CYP2C9) substrates)
Interaction Rating=Moderate Be cautious with this combination.
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.
Medications changed by the liver (Cytochrome P450 2D6 (CYP2D6) substrates)
Interaction Rating=Moderate Be cautious with this combination.
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.
Medications changed by the liver (Cytochrome P450 3A4 (CYP3A4) substrates)
Interaction Rating=Moderate Be cautious with this combination.
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.
Medications moved by pumps in cells (P-glycoprotein Substrates))
Interaction Rating=Moderate Be cautious with this combination.
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.
Herbs and supplements that might lower blood pressure: Quercetin might lower blood pressure. Taking it with other supplements that have the same effect might cause blood pressure to drop too much. Examples of supplements with this effect include andrographis, casein peptides, L-arginine, niacin, and stinging nettle.
Herbs and supplements that might lower blood sugar: Quercetin might lower blood sugar. Taking it with other supplements with similar effects might lower blood sugar too much. Examples of supplements with this effect include aloe, bitter melon, cassia cinnamon, chromium, and prickly pear cactus.
There are no known interactions with foods.
Quercetin has most often been used by adults in doses of 250-1000 mg by mouth daily for up to 12 weeks. Speak with a healthcare provider to find out what dose might be best for a specific condition.
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.
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