Most All My information for Histamine Intolerance and MCAS comes from MastCell360.com
"When a patient with a mast cell disorder is exposed to a trigger or triggers, their mast cells degranulate inappropriately. This causes them to release dozens or more chemicals, including histamine, trypase, heparin, prostaglandins, neutral proteases, acid hydrolases, tumor necrosis factor, including anaphylaxis, and even fatal toxic shock. TRIGGERS ARE BAD.
Triggers can be various and hard to pinpoint but by careful tracking, a patient can usually begin to see a pattern emerge. Food, medicines, stress, sunlight, and exercise can all trigger the mast cells to degranulate and this can cause a mild to severe reaction. REACTIONS CAN BE FATAL.
Sometimes a reaction isn't immediate and can take hours or even days to manifest. Some triggers don't cause any symptoms until a certain amount of exposure takes place or if they are combined with another trigger. For instance, exercising while outside in the sunshine or eating too much of a certain food. Medications may not trigger a reaction until a few days or weeks into taking it. HARD TO PREDICT.
This is what is known as the "degranulation bucket overlaod." Similiar to the "histamine bucket" in allergies. The degranulation bucket overflows when too many triggers or too much of one trigger causes a reaction. It is very difficult to keep this from happening due to the nature of mast cell disease. Triggers can change over time and what effects us badly one day may not do so another day for no apparent reason. WE DEGRANULATE."