What is Mast cell activation syndrome? It is a condition in which the mast cells in your body release too much of a substance that causes allergy symptoms. Mast cells are part of your immune system. They’re found throughout our bodies, particularly in bone marrow and around blood vessels. When you’re exposed to allergens or similar substances in food, medications, or insect venom, your mast cells react by releasing substances called mediators. Mediators cause symptoms of an allergic reaction, including itching, mucus, and inflammation. If you have MCAS, your mast cells release mediators too frequently and too often.
MCAS symptoms impact many body parts including the skin, eyes, nose, mouth, throat, lungs, hearts, blood vessels, nervous system, stomach and intestines. The stomach and intestinal symptoms include nausea, diarrhea, cramping, and abdominal pain. Most people with hEDS also have MCAS, so keeping away from foods, fluids, and medicines that cause sensitivity and reaction is obviously beneficial.