Mast Cell Activation Syndrome (MCAS)

Mast cells are in every area of the body, and are a needed part of the immune system's defense. However, Mast Cell Activation Syndrome (most often called secondary MCAS) is a condition where these mast cells severely over-release excessive amounts of chemical mediators like histamine, prostaglandins, leukotrienes, cytokines, and hundreds more. It is called secondary because something such as an environmental trigger, virus, stress, or multiple chronic conditions causes mast cells to become over-sensitized. This causes systemic symptoms across multiple organs without one clear trigger. Symptoms can cover skin, gastrointestinal, cardiovascular, respiratory, and neurological systems.

Due to the heavy histamine release, many of the symptoms correlate with allergic symptoms such as itching, hives, sneezing, reactivity to high-histamine foods, asthma, restrictive airways, and even anaphylaxis. These mediators are also very concentrated around the heart and lungs, and can result in painful breathing, tightness of chest, burning sensations, and in more serious conditions, pinched arteries and pericarditis.

The symptoms are quite exhaustive, but some other more common ones are GI disruption, nausea, delayed stomach emptying, diarrhea or constipation, endometriosis, sensitivity to smell, noise, light, or heat, fibromyalgia, chronic fatigue, pain in joints, or burning sensations on the skin. Most people with MCAS don't have all of these symptoms at once, and due to the broad array of symptoms, it can take patients years to be properly diagnosed.

Keeping a journal of symptoms and what may have caused them can be key to getting to the root cause (though root cause is nuanced here, as MCAS is rarely a root cause in itself).

While MCAS is recently getting more focus, many doctors, allergists, and immunologists will now claim they know what it is and how to treat it. What they really mean to say is they know it creates excess histamine and taking H1 and H2 blockers can help with symptoms, as well as prescribing a mast cell stabilizer. While these can certainly help short term, it is not getting to the cause, nor the triggers. Avoiding and removing triggers is key to lowering the MCAS load. All the potential triggers listed above can safely be limited or removed to see how the patient responds.

Working with a specialist who understands the full picture—often in trio with POTS and hEDS—the role of genetics, mold, or other environmental triggers, is a must to truly find answers.

While there is primary MCAS (a more rare, genetic condition) and systemic mastocytosis (also genetic but different in several key areas), there is also idiopathic MCAS (essentially caused from an unknown reason, but this really just means the doctor has not yet been able to identify the trigger, which is certainly there, putting it into the secondary category). You can read more about the differences here.

One of the most disorienting aspects of MCAS is how unpredictable it is. Symptoms can change daily — even hour to hour. A food tolerated perfectly one day may trigger a severe reaction the next. Pain can fluctuate constantly, migrating through the body without warning, and the threshold for what the body can handle shifts with stress, sleep, environment, and exposure. This variability is not in the patient's head; it is the nature of a mast cell system that has lost its baseline stability.

Those with the MCAS, dysautonomia, and hEDS "trifecta" are often compensating constantly — bracing joints, managing heart rate and blood pressure swings, navigating food and chemical sensitivities, and pushing through layers of pain and discomfort that most people never experience. The cumulative load is exhausting, and because the symptoms are invisible and shifting, patients are frequently left feeling that no one truly understands the daily weight they carry.

MCAS is still severely misunderstood, misdiagnosed, and dismissed. Patients are routinely told their symptoms are anxiety, stress, or "all in their head" — a form of medical gaslighting that delays proper care for years. Dr. Anne Maitland, an allergist/immunologist and leading MCAS clinician, has spoken openly about how MCAS patients are so often dismissed by the conventional system, how their fluctuating, multi-system symptoms are written off because they don't fit neatly into one specialty's box, and how this dismissal causes real harm. Dr. Ina Stephens, a physician specializing in EDS and connective tissue disorders, echoes this — emphasizing that the variability and invisibility of MCAS are exactly why it requires a practitioner who listens, who looks at the whole picture, and who understands that a normal lab panel does not mean a normal body.

Through personal experience and success, The Health Konnector believes MCAS can nearly always be put in remission if it is secondary. Remission is slow but sure. There is so much hope in the future with MCAS. Searching for the root and removing the triggers will certainly bring some symptom relief.