MCAS is a condition in which mast cells in the body activate inappropriately and release substances. This causes a wide range of symptoms that often resemble allergic reactions. Examples include skin complaints such as redness and itching, circulatory complaints such as low blood pressure and fainting, gastrointestinal complaints such as abdominal cramps and diarrhea, respiratory complaints such as a stuffy nose or itching in the nose, and other symptoms such as fatigue, concentration problems, and a general feeling of illness. View our page about MCAS here for more information.
