Mast cell activation syndrome (MCAS) is when your mast cells overreact with no known trigger. It causes severe symptoms and can lead to life-threatening anaphylaxis.

Symptoms of MCAS are caused by excessive chemical mediators released by mast cells. [10] Mediators include leukotrienes, histamines, prostaglandin, and tryptase.

Mast Cell Activation Syndrome (MCAS) happens with repeated symptoms of anaphylaxis – allergic symptoms such as hives, swelling, low blood pressure, difficulty breathing and severe diarrhea.

May 27, 2024 · Mast cell activation syndrome, also called MCAS or mast cell activation disorder, is a condition that causes mast cells to release high amounts of chemicals into your body.

Nov 3, 2025 · Mast cell activation syndrome (MCAS) is a disorder in which mast cells, a normal type of cell found in your immune system, release excessive amounts of histamines and other chemicals …

Feb 27, 2025 · Did you know that Mast Cell Activation Syndrome (MCAS) often doesn’t travel alone? It’s a common comorbidity to conditions like Ehlers-Danlos Syndrome (EDS), Postural Orthostatic …

MCAS is considered a multi-systemic condition, which means that two or more body systems are affected at the same time during a reaction. Because of the complex pattern of symptoms, no two …