Food sources that contain quercetin include apples, onions, berries, broccoli, cherries, coffee, citrus, grapes, grapeseed, bilberry, ginkgo biloba, and green tea. It can also be found as a dietary supplement for easy consumption in powder and capsule form.

The plant that contains quercetin is dried and made into a fine powder and placed into a capsule. The capsules may also contain bromelain (an enzyme found in pineapple) because both quercetin and bromelain have anti-inflammatory properties.

According to the Mount Sinai Health Library, if you are taking any of the following medications, you should not use quercetin supplements without talking to your healthcare provider: antibiotics, anticoagulants (blood thinners), chemotherapy medication, corticosteroids, cyclosporine, digoxin, fluoroquinolones, medications that are changed by the liver*

*Since quercetin affects the liver, concomitant use with medications that are changed by the liver may impact how the body absorbs these medications.