What is quercetin ?

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.

What are the uses & effectiveness ?

Possibly Ineffective for Athletic performance. Taking quercetin by mouth before exercise doesn't decrease fatigue or improve exercise ability. There is interest in using quercetin for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful.

What are the side effects?

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.

What are the precautions and warnings?

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. 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.

What are the interactions?

Moderate InteractionBe cautious with this combination Antibiotics (Quinolone antibiotics) interacts with QUERCETIN Some scientists think that taking quercetin along with certain antibiotics, called quinolone antibiotics, might decrease the effects of these antibiotics. But it's too soon to know if this is a big concern. Cyclosporine (Neoral, Sandimmune) interacts with QUERCETIN Quercetin might decrease how quickly the body breaks down cyclosporine. Taking quercetin with cyclosporine might increase the effects and side effects of cyclosporine. 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 change how quickly the liver breaks down these medications. This could change the effects and side effects of these medications. 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 change how quickly the liver breaks down these medications. This could change the effects and side effects of these medications. 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 change how quickly the liver breaks down these medications. This could change the effects and side effects of these medications. 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 change how quickly the liver breaks down these medications. This could change the effects and side effects of these medications. Medications moved by pumps in cells (P-Glycoprotein substrates) interacts with QUERCETIN Quercetin medications are moved in and out of cells by pumps. Quercetin might change how these pumps work and change how much medication stays in the body. In some cases, this might change the effects and side effects of a medication. Warfarin (Coumadin) interacts with QUERCETIN Quercetin might increase the effects that warfarin has on the body. Taking quercetin and warfarin together might increase the effects and side effects of warfarin, which could increase the risk of bruising and bleeding. Medications for high blood pressure (Antihypertensive drugs) interacts with QUERCETIN Quercetin might lower blood pressure. Taking quercetin along with medications that lower blood pressure might cause blood pressure to go too low. Monitor your blood pressure closely. Medications moved by pumps in cells (Organic anion-transporting polypeptide substrates) interacts with QUERCETIN Some medications are moved in and out of cells by pumps. Quercetin might change how these pumps work and change how much medication stays in the body. In some cases, this might change the effects and side effects of a medication. Midazolam (Versed) interacts with QUERCETIN Quercetin might increase how quickly the body breaks down midazolam. Taking quercetin with midazolam might reduce the effects of midazolam. Pravastatin (Pravachol) interacts with QUERCETIN Quercetin might decrease how quickly the body gets rid of pravastatin. Taking quercetin with pravastatin might increase the effects and side effects of pravastatin. Medications for diabetes (Antidiabetes drugs) interacts with QUERCETIN Quercetin might lower blood sugar levels. Taking quercetin along with diabetes medications might cause blood sugar to drop too low. Monitor your blood sugar closely. Diclofenac (Voltaren, others) interacts with QUERCETIN Quercetin might decrease how quickly the body breaks down diclofenac. Taking quercetin with diclofenac might increase the effects and side effects of diclofenac. Losartan (Cozaar) interacts with QUERCETIN Quercetin might change how the body absorbs and breaks down losartan. Taking quercetin with losartan might change the effects and side effects of losartan. Quetiapine (Seroquel) interacts with QUERCETIN Quercetin might increase levels of quetiapine. Taking quercetin and quetiapine together might increase the effects and side effects of quetiapine. Medications moved by pumps in cells (Organic Anion Transporter 1 (OAT1) Substrates) interacts with QUERCETIN Some medications are moved in and out of cells by pumps. Quercetin might change how these pumps work and change how much medication stays in the body. In some cases, this might change the effects and side effects of a medication. Medications moved by pumps in cells (Organic Anion Transporter 3 (OAT3) Substrates) interacts with QUERCETIN Some medications are moved in and out of cells by pumps. Quercetin might change how these pumps work and change how much medication stays in the body. In some cases, this might change the effects and side effects of a medication. Mitoxantrone interacts with QUERCETIN Quercetin might increase levels of mitoxantrone. Taking quercetin and mitoxantrone together might increase the effects and side effects of mitoxantrone. Prazosin (Minipress) interacts with QUERCETIN Quercetin might increase levels of prazosin. Taking quercetin and prazosin together might increase the effects and side effects of prazosin. Sulfasalazine (Azulfidine) interacts with QUERCETIN Quercetin might increase levels of sulfasalazine. Taking quercetin and sulfasalazine together might increase the effects and side effects of sulfasalazine.

What is the dosing?

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.