This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
Mast cell activation syndrome (MCAS) causes a person to have repeated severe allergy symptoms affecting several body systems. In MCAS, mast cells mistakenly release too many chemical agents, resulting in symptoms in the skin, gastrointestinal tract, heart, respiratory, and neurologic systems. Mast cells are present throughout most of our bodies and secrete different chemicals during allergic reactions. Symptoms include episodes of abdominal pain, cramping, diarrhea, flushing, itching, wheezing, coughing, lightheadedness and rapid pulse and low blood pressure. Symptoms can start at any age, but usually begin in adulthood. The cause of MCAS is unknown. Diagnosis is based on the symptoms, clinical exam, and specific laboratory testing. Other conditions may need to be excluded before MCAS can be diagnosed. Treatment includes several combinations of medications used for allergic reactions, such as antihistamines and mast cell stabilizers.
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