What is it?

Mast cell activation syndrome (MCAS) is a condition in which mast cells, which are a part of the immune system, release too much of the substance inside it. Mast cells are found in the bone marrow and respond to stress or danger by releasing mediators that cause inflammation. In MCAS, the body releases too many mediators too often. The reason for these conditions is unknown, but it may be due to a genetic factor. Risk factors include allergic-type triggers, drug-induced triggers, anxiety, pain, exercise, infection, smells, hormonal changes and mast cell hyperplasia due to chronic infections or malignancies.