Histamine

A chemical released by mast cells when they are activated. HistamineHistamine A chemical released by mast cells when they are activated. Histamine causes many of the allergy-type symptoms in mastocytosis, including flushing, itching and hives. causes many of the allergy-type symptoms in mastocytosisMastocytosis Rare disease caused by the buildup of mast cells. Cutaneous mastocytosis primarily affects the skin and is more common in children, while systemic mastocytosis affects internal organs and is more common in adults., including flushing, itching and hives.