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.

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.

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

The current consensus diagnostic criteria for mast cell activation syndrome (s) (MCAS [s]) were first established in 2012 and updated in 2019. This diagnosis has been attached to multiple medical …

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 …

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, …

Nov 9, 2025 · Signs and symptoms of mast cell activation syndrome (MCAS) include itching, hives, and digestive issues. These symptoms can mimic allergic reactions like anaphylaxis.

Mar 31, 2025 · Mast cell activation syndrome, or disease (MCAS), is a condition that causes mast cells to release these substances too frequently, resulting in severe allergic reactions.