Guidelines on quercetin dosage are limited, because it is treated as a dietary supplement and has not been subjected to rigorous clinical trials. Studies on the supplement indicate that doses above 1 gram a day can be dangerous for the kidneys, and it is advisable for people to take periodic breaks to avoid continuous use. The best dosage can depend on how well someone responds to quercetin, as well as existing health issues that might necessitate a lower dosage or could be contraindications for using the supplement at all.
Studies indicate quercetin can act as an antiinflammatory and antihistamine. It may be beneficial in the treatment of prostate and bladder inflammations, and could help people manage allergies and asthma. Any dietary supplement should be discussed as part of a larger care plan if a patient has an existing medical problem. It may not be safe to take, or there might be a better way to control symptoms to eliminate the need for a supplement.
Typically a quercetin dosage is divided over the day. Patients can take between two and three doses with food. This increase absorption. If a reaction does occur, it is important to take note of any other medications, including supplements, taken at the same time. If any unusual foods were eaten or something else was abnormal about the day, this could be important to know about as well, because this might be the cause of the reaction.
Kidney damage is a concern with this flavanoid, a plant pigment found in the natural environment. In the small traces present in food, there is not enough to pose a health risk, but taking purified supplements with a higher quercetin dosage can potentially damage the kidneys. People with existing kidney problems, or who use medications metabolized in the kidneys, may not be able to take it. Quercetin dosage may also need to be reduced for patients with liver problems, or who take medications processed by the liver, because it can interfere with metabolism.
Pregnant and breastfeeding women should avoid quercetin because there is not enough information on its safety for developing fetuses and children. For the same reason, a quercetin dosage is not usually recommended for children, due to lack of data. Patients taking chemotherapy or anticoagulant medications could also be at risk of drug conflicts and might not be able to take the supplement. There may be other cases where a care provider will recommend against taking quercetin due to concerns about conflicts.