MCAS triggers

There are several factors that may act as mast cell activation triggers, resulting in release of mast cell mediators, leading to the symptoms and complications of mast cell activation syndrome (MCAS). Triggers may include but are not limited to, certain foods, alcohol, medications, radiocontrast dyes, odours, insect stings, infections, hormones, exercise as well as physical and emotional stress.^1,2,17

Individual triggers are often highly variable and can be difficult to identify, particularly in cases of secondary or idiopathic MCAS. In these forms, mediator release from abnormal mast cell activation may be influenced by underlying health conditions, immune dysregulation, and environmental factors. This can make trigger identification a complex and ongoing process, and in some patients, there are no clear triggers despite careful tracking.¹⁵

Identifying triggers

Determining and managing triggers in MCAS is often complex and typically involves a process of trial and error. There is no single list of foods, hormones, environmental exposures, or lifestyle factors that will cause symptoms in all patients with MCAS.^2,17,18 Triggers and their severity can vary widely, even among patients within the same subtype.

As social awareness of MCAS increases, an influx of information is being shared online including about trigger identification and management. Some sources, including those published by healthcare professionals, promote extensive lists of potential triggers as if they are universally applicable or inherently beneficial. This is incorrect and non-discerning implementation of such advice is often harmful and provides no benefit.¹⁹

While TAMS supports patients being informed and taking an active role in their care, we strongly advise against adopting broad or extreme potential trigger avoidance strategies without due cause. In the absence of a confirmed history of anaphylaxis, avoiding potential triggers such as entire food groups, physical activity, or common environmental exposures such as sun, may not improve outcomes and can negatively affect overall health and quality of life.²⁰

To avoid unnecessary risk, we encourage you to consult your treating specialist before making significant changes to your lifestyle or daily routines. If you are waiting to see a specialist, keeping a record of your symptoms and any suspected triggers may be a more practical and safe way to support informed discussions during your future appointments.