Quercetin Safety

Quercetin is a plant-based flavonoid found in apples, onions, teas, red wines and some other foods. It can also be taken as a dietary supplement for its effectiveness as an anti-inflammatory and antioxidant.

Dosage

• Quercetin supplements are not regulated by the U.S. Food and Drug Administration. Therefore, the amount of quercetin in a particular supplement might not be the amount that is claimed. High doses of quercetin can cause nausea and kidney damage. If you experience such symptoms, stop taking quercetin and consult your doctor.

Cancer Treatment

• Quercetin's activity in cell culture studies has suggested that the compound can reduce the growth of some types of cancer, or even cause the death of such cancers, possibly because of its antioxidant or anti-inflammatory properties. Quercetin also might prevent colon cancer. However, more studies are needed, and the American Cancer Society cautions that quercetin should not be relied on as a primary cancer treatment. If you are exhibiting the signs of any type of cancer, seek medical attention.

Vitamin C Sensitivity

• People who are react badly to Vitamin C or citrus fruits might experience side effects when taking a quercetin supplement. These can include digestive problems, sores in the mouth and headaches. If you experience these side effects, stop taking quercetin and consult your doctor.

Other Side Effects

• Other possible side effects of quercetin include tingling of the arms and legs. Quercetin also might decrease the effectiveness of certain antibiotics and could alter the way the body absorbs other drugs. Consult your doctor when taking a quercetin supplement in addition to other medicines.