What Is Mast Cell Activation Syndrome?

One viewer is asking what mast cell activation syndrome (MCAS) is and what symptoms come along with it. Dr. Lacy Anderson responds.

Mast cell activation syndrome is a condition where people have recurrent symptoms of terrible allergic reactions.  

It can cause symptoms of anaphylaxis which is a life-threatening allergic reaction. It can also cause hives, swelling, low blood pressure, shortness of breath, and diarrhea. 

During these episodes, high levels of mast cells are released which are causing the allergic reaction. These events can occur even without any allergy triggering the response. 

The cause of this is unknown but if you have this condition, you should carry an Epipen at all times in case you have a severe reaction.  

Allergy medications like antihistamines are often used for symptoms as well as leukotriene-blockers like singulair. A newer medication called Xolair seems to be working very well for people with MCAS. Xolair is a monoclonal antibody injection used every two to four weeks.  

Mast cell activation syndrome will likely need to be diagnosed and treated by an allergist so if you think you might have this, I’d recommend you get an allergy consult as soon as possible.