From the Manufacturer's Label:
Quercetin is a naturally occurring bioflavonoid that supports healthy histamine levels, thereby helping to sustain a balanced immune response.** Bromelain, an enzyme derived from pineapple stems, also supports healthy immune system function.** The combination of Quercetin and Bromelain therefore provides powerful immunomodulating.**
Manufactured by Now® Foods.Citrus Free. Contains no sugar, salt, yeast,wheat, gluten, corn, soy, milk, egg, shellfish or preservatives.