• Welcome to Phoenix Rising!

    Created in 2008, Phoenix Rising is the largest and oldest forum dedicated to furthering the understanding of, and finding treatments for, complex chronic illnesses such as chronic fatigue syndrome (ME/CFS), fibromyalgia, long COVID, postural orthostatic tachycardia syndrome (POTS), mast cell activation syndrome (MCAS), and allied diseases.

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Mast Cell Activation (MCAS)

Mast cells are immune cells that are involved in allergic reactions such as hives, anaphylaxis, dermatographia, and sometimes intestinal inflammation. Mast cells can become activated by two things: allergens or autonomic nerves. Mast Cell Activation Syndrome (MCAS) is a condition defined by abnormal mast cell activation and allergic reactions - but without any obvious allergic cause. (For allergic reactions with a known cause, see the "Immunology, Inflammation, Allergies" forum.)