Mast Cell Activation Syndrome (MCAS)

Mast Cell Activation Syndrome (MCAS) is a condition where mast cells—part of the immune system—inappropriately release excessive amounts of chemical mediators like histamine, leukotrienes, and cytokines. This causes systemic, allergic-like symptoms across multiple organ systems, often without a clear allergic trigger.

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Common Symptoms

Skin: Hives, flushing, itching, sweating

Gastrointestinal: Nausea, vomiting, diarrhea, abdominal cramping

Cardiovascular: Rapid heart rate, low blood pressure, fainting

Respiratory: Wheezing, shortness of breath, nasal congestion

Neurological: Brain fog, headaches, fatigue, anxiety

Causes & Triggers

Environmental triggers (mold, strong odors, temperature changes)
Food and beverages (high histamine foods, alcohol)
Stress (physical and emotional)
Infections and viruses
Medications and excipients

Diagnosis

Diagnosis typically involves a clinical evaluation of symptoms across at least two organ systems, laboratory evidence of elevated mast cell mediators (e.g., serum tryptase, 24-hour urine histamine, prostaglandins) during a flare, and a positive response to medications that block mast cell mediators.

Treatment Approaches

Identifying and avoiding triggers

H1 and H2 antihistamines (e.g., Cetirizine, Famotidine)

Mast cell stabilizers (e.g., Cromolyn sodium, Ketotifen)

Leukotriene inhibitors (e.g., Montelukast)

Dietary modifications (low histamine diet)

Not Sure Where to Start?

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