Quercetin is a type of flavonoid — an antioxidant found in fruits and vegetables. In laboratory research, quercetin stopped immune cells called mast cells from releasing histamine. In theory, this supplement might prevent allergy symptoms, although studies haven’t yet proven its usefulness.
Quercetin is generally safe. Most side effects are mild, such as headache or upset stomach. At very high doses, quercetin can cause kidney damage.
March 30, 2020
Janet O’Dell, RN