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Mast Cell Activation Syndrome, or MCAS, is a condition where the body’s mast cells become overactive and release chemicals that affect multiple body systems. Mast cells normally help regulate allergic and inflammatory responses, but in MCAS they may trigger symptoms without clear warning or known allergens.
MCAS can affect people of any age and is often seen in individuals with complex chronic health conditions. It tends to appear in people who also live with POTS, hypermobile Ehlers-Danlos syndrome, Hypermobility Spectrum Disorder, or ME/CFS.
Diagnosing MCAS can be challenging. Although international diagnostic guidelines exist, access to the specialised testing needed is limited in Australia. For many people, diagnosis is based on clinical symptoms and observing whether those symptoms respond to treatment with medications that reduce mast cell activity.
Symptoms vary from person to person but may include:
Symptoms may be triggered by heat, stress, certain foods, infections, exercise, or hormonal changes. They often come in unpredictable flares.
There is a strong association between MCAS and autonomic disorders like POTS. For some people, mast cell flares appear to make POTS symptoms worse, leading to increased dizziness, heart rate changes, and fatigue. Managing MCAS can help reduce the frequency or intensity of these episodes and improve symptom stability.
If you think MCAS may be part of your health picture, speak with your healthcare provider about your symptoms and response to treatment. For more resources and support, visit The Australian Mastocytosis Society.