Mast Cell Activation: Symptoms, Root Causes, and What You Can Do About It

This video gives a patient-friendly explanation of mast cell activation syndrome (MCAS): what mast cells are, where they are located in the body, what triggers them, and how their activation leads to multi‑system symptoms. Mast cells live in tissues that interface with the outside world (skin, gut, airways, bladder, blood vessels and nerves) and release chemicals like histamine when triggered by infections, allergens, physical stimuli, stress, temperature changes, or sometimes seemingly no clear cause. The video walks through symptoms by organ system—skin flushing, hives, swelling, GI pain and diarrhea, respiratory symptoms, bladder pain/interstitial cystitis, cardiovascular changes, and anaphylaxis—and explains why reactions can vary in intensity from day to day. It clarifies what anaphylaxis is, why it is dangerous, and the need for emergency treatment (e.g., epinephrine).

In terms of management, Dr. Clair outlines a stepwise approach starting with first-line medications: H1 antihistamines (like cetirizine, loratadine) and H2 blockers (like famotidine) to reduce histamine effects. She then discusses second-line mast cell stabilizers, especially cromolyn sodium, which can decrease mast cell degranulation over time. Additional medications sometimes used for MCAS (such as leukotriene receptor antagonists and others) are briefly mentioned as options for more complex cases under specialist care. The video also highlights a low-histamine diet as a common nonpharmacologic strategy, with practical advice to track food and symptom patterns and an explanation of why people may tolerate a given food on some days but not others (total histamine load, other triggers, and baseline mast cell irritability). MCAS connections with bladder symptoms/interstitial cystitis and with hypermobility/EDS communities are noted, and viewers are directed to The Ehlers-Danlos Society and related resources to find knowledgeable clinicians and further education. The content is framed as educational only and not a substitute for individualized medical care.