Conventional Medical Treatments for Mast Cell Activation Syndrome


What is mast cell activation syndrome?

Mast cell activation syndrome (MCAS) is a condition that impacts the body’s mast cells. Mast cells grow in the skin, airway, gastrointestinal tract, and bone marrow. They are blood cells that play a part in the immune system, and are also involved in allergic reactions. They release chemicals called “mediators” when the body encounters an allergen.

In mast cell activation syndrome, the mast cells release too many mediators when exposed to allergens or other substances, resulting in severe allergy symptoms. This causes problems with the heart, skin, neurologic system, and gastrointestinal tract. Although there is no cure for MCAS, treatment typically involves the avoidance of triggers and medication for symptom management.

Conventional medical treatments for MCAS

While currently there is no cure for mast cell activation syndrome, medications are the most accepted treatment plan. The overall goal of treatment is to provide symptom relief. If an individual does not respond to medication treatment, MCAS is not likely present.


Medications used for MCAS treatment commonly include, but are not limited to, the following:

  • H-1 receptor antagonists (first-generation)
    H-1 receptor antagonists first-generation prevent the release of histamine by binding to the histamine receptors in the spinal cord and brain. They are referred to as first-generation because they were the first antihistamines to be approved by the FDA. They treat general allergy symptoms and can cause drowsiness. Examples include diphenhydramine and hydroxyzine.
  • H-1 receptor antagonists (second-generation)
    Developed in the 1980s, H-1 receptor antagonists second-generation are the second type of antihistamine approved by the FDA. They also prevent the release of histamine by binding to the histamine receptors in the spinal cord and brain. Second-generation antihistamines are safer than first-generation because they do not cross the blood-brain barrier, which causes drowsiness. They also interact safer with other medications. Effectiveness can last up to 24 hours and is generally more successful in treating allergy symptoms. Examples include loratadine, cetirizine and fexofenadine.
  • H-2 receptor antagonists
    H-2 receptor antagonists work by blocking histamine-induced gastrointestinal conditions, such as motion sickness, vomiting, gastroesophageal reflux, and gastric ulcers. They also reduce nausea and abdomen pain. Examples include ranitidine and famotidine.
  • Aspirin
    Aspirin reduces flushing, or skin reddening, associated with MCAS. It also blocks production of prostaglandin D2, which is an inflammatory mediator.
  • Leukotriene modifiers
    Also known as leukotriene receptor antagonist, this class of medication blocks the effects of leukotrienes. Leukotriene is a mediator that causes inflammation of the airway, resulting in wheezing, coughing, and mucus buildup. Examples include montelukast, zafirlukast and zileuton.
  • Corticosteroid
    Also known as steroids, corticosteroids are anti-inflammatory medications used to treat edema, hives and wheezing. This medication should only be used as a last resort.
  • Omalizumab
    Omalizumab is an anti-inflammatory medication that works by binding immunoglobulin E (IgE) to its receptors. It can reduce the reactivity of mast cells and block actions of certain substances, which can lower the risk of anaphylaxis.

Individuals who experience anaphylaxis should carry an epinephrine auto-injector with them at all times. They should also consult a health care professional about the steps to take in the event of a severe reaction.

Additional sources: RxList, American Academy of Allergy, Asthma and Immunology, and RxList

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