Mast Cell Activation Syndrome Treatment Guidelines

Diagnosis and Manifestations

Mast Cell Activation Syndrome (MCAS) is characterized by recurrent episodes of systemic anaphylaxis concurrently affecting at least 2 organ systems, resulting from secreted mast cell mediators, according to the Journal of Allergy and Clinical Immunology 1
Common manifestations of MCAS include cardiovascular, respiratory, dermatologic, and gastrointestinal symptoms, as reported by the Journal of Allergy and Clinical Immunology 1

The American Academy of Allergy, Asthma, and Immunology recommends H1 antihistamines (non-sedating preferred) as first-line for most symptoms, which can be increased to 2-4 times the standard dose, as suggested by Praxis Medical Insights 2
H2 antihistamines are recommended for gastrointestinal symptoms and to help attenuate cardiovascular symptoms, as stated by Praxis Medical Insights 2
Epinephrine autoinjectors should be prescribed for patients with a history of systemic anaphylaxis or airway angioedema, according to Praxis Medical Insights 2
Leukotriene modifiers (montelukast, zileuton) may reduce bronchospasm and gastrointestinal symptoms, as reported by Praxis Medical Insights 2
Aspirin should be used with caution as it can trigger mast cell degranulation in some patients, as noted by the Journal of Allergy and Clinical Immunology 3

Omalizumab is the most studied biologic for refractory MCAS, shown to reduce severity and frequency of allergic reactions, as reported by the Journal of Allergy and Clinical Immunology 3

Treatment should be guided by symptoms and specific elevated mediator levels, as suggested by Praxis Medical Insights 2
Long-term steroid use should be avoided due to side effects, as stated by Praxis Medical Insights 2
Consider multidisciplinary management involving allergy specialists and other relevant specialists, as recommended by Praxis Medical Insights 2