What Is MCAS? Understanding Mast Cell Activation Syndrome and the Benefits of Multidisciplinary Care

Written by Megan Stranski, Psy.D.
Licensed Clinical Psychologist
GI Psychology

If you or your child experiences a combination of gastrointestinal (GI) symptoms, allergic-type reactions, flushing, itching, dizziness, or episodes that seem to affect several parts of the body, you may have heard the term mast cell activation syndrome (MCAS).

MCAS can be a complex and sometimes confusing condition. Symptoms may involve multiple body systems and can change over time. Because many of these symptoms can also occur with other medical conditions, diagnosis requires careful evaluation by a healthcare professional with experience in mast cell disorders.

Living with unpredictable symptoms can also affect much more than physical health. It may influence eating, sleep, school or work, relationships, daily activities, and emotional well-being.

This is one reason a multidisciplinary approach can be helpful. A multidisciplinary team brings together professionals with different areas of expertise to address both the medical aspects of symptoms and the ways those symptoms affect everyday life.

What Are Mast Cells?

Mast cells are immune cells that help the body respond to potential threats. They are found throughout the body, including in the skin, respiratory system, and gastrointestinal (GI) tract.

When mast cells become activated, they release substances called mediators. These include chemicals such as histamine, tryptase, prostaglandins, and leukotrienes. These substances play important roles in immune and inflammatory responses. When mast-cell mediators are released during an acute reaction, they can contribute to symptoms such as itching, flushing, hives, swelling, abdominal cramping, nausea, vomiting, diarrhea, rapid heart rate, low blood pressure, wheezing, or shortness of breath (Hamilton, 2024; Valent et al., 2019).d on symptom patterns (Rome IV criteria), after ruling out other medical conditions (Rome Foundation, 2016).

So, What Is MCAS?

Mast cell activation syndrome (MCAS) is a condition characterized by recurrent episodes of symptoms caused by the release of mast-cell mediators.

Importantly, having symptoms that can occur with mast-cell activation does not automatically mean someone has MCAS. Many of these symptoms are common and can have a variety of causes, which is why appropriate medical evaluation is important.

Consensus-based approaches generally consider three key components when evaluating MCAS:

Symptoms consistent with mast-cell activation, typically involving more than one body system.
Objective evidence of mast-cell mediator release during an episode. This may include an appropriate increase in serum tryptase or other validated mediator testing. For tryptase, clinicians commonly look for a significant rise from the individual’s baseline level.
Improvement with treatment that targets mast-cell mediators.

Additional evaluation may be needed to determine whether symptoms are related to an allergic condition, a clonal mast-cell disorder such as systemic mastocytosis, or another medical condition that can cause similar symptoms (Valent et al., 2019; Valent et al., 2020).

Because MCAS diagnosis and testing can be complicated, it is best to work with an allergist/immunologist or another healthcare professional experienced in evaluating mast-cell disorders.

What Might MCAS Symptoms Look Like?

Symptoms can vary considerably from person to person. Possible symptoms include:

Skin: flushing, itching, hives, or swelling
GI: abdominal pain or cramping, nausea, vomiting, or diarrhea
Cardiovascular: rapid heart rate, lightheadedness, low blood pressure, or fainting
Respiratory: wheezing, shortness of breath, or throat symptoms

Importantly, these symptoms are not specific to MCAS. Experiencing one or more of these symptoms does not, by itself, establish a diagnosis.

Why Can MCAS Be So Difficult to Navigate?

One reason MCAS can feel overwhelming is that symptoms may occur across different body systems. A person may see an allergist for flushing or allergic-type symptoms, a gastroenterologist for abdominal pain, and another provider for dizziness or other concerns.

Each symptom is important, but when several healthcare professionals are involved, care can sometimes feel fragmented.

Patients and families may understandably wonder:

“Why am I reacting to this food today but not last week?”
“Why does my stomach hurt when my allergy tests are normal?”
“Why do my symptoms seem worse when I’m stressed?”
“Am I imagining these symptoms?”
“Why does one treatment help one symptom but not another?”

These questions deserve thoughtful answers.

The goal of multidisciplinary care is not to decide that symptoms are “all in your head.” Instead, it recognizes that the immune system, GI system, nervous system, and emotional experiences can all influence a person’s overall experience of illness.

The Gut-Brain Connection: Where Does a GI Psychologist Fit?

The brain and gastrointestinal tract communicate continuously through what is commonly called the gut-brain axis. This communication involves the nervous system, immune signaling, hormones, and other biological pathways.

Stress does not mean that GI symptoms are imaginary. Stress and other forms of nervous-system activation can influence GI function and can affect how strongly the brain responds to signals coming from the GI tract.

This can be especially relevant when someone is living with unpredictable or uncomfortable GI symptoms.

A GI psychologist is a psychologist who specializes in the relationship between gastrointestinal health, the brain, behavior, and emotional well-being. GI psychologists do not diagnose MCAS or replace medical treatment. Instead, they can work alongside medical providers to address the brain-gut and behavioral aspects of living with GI symptoms.

Brain-gut behavioral therapies—including approaches such as cognitive behavioral therapy and gut-directed hypnotherapy—are evidence-based treatments for several disorders of gut-brain interaction and can help with GI symptoms, coping, and quality of life. Research in this area does not mean that these therapies treat the underlying mast-cell disorder itself. Rather, they may be useful for addressing the GI and quality-of-life challenges that can occur alongside complex medical conditions (Keefer et al., 2022).

How Can a GI Psychologist Help Someone Living With MCAS?

1. Understanding the gut-brain connection

Education can be an important part of treatment.

A GI psychologist can help patients understand how the nervous system may become more alert or vigilant after repeated experiences of pain, nausea, diarrhea, allergic-type reactions, or other uncomfortable sensations.

For example, someone who has experienced sudden abdominal pain may begin monitoring their stomach throughout the day:

“Does my stomach feel different?”

“Was that food safe?”

“What if I start having symptoms while I’m away from home?”

This increased monitoring is understandable. Over time, however, it can become exhausting and may make it difficult to focus on other parts of life.

GI psychology can help patients develop a more balanced relationship with body sensations while continuing to take legitimate physical symptoms seriously.

2. Reducing fear and anticipatory anxiety

When symptoms are unpredictable, it is natural to begin bracing for the next episode.

A patient may avoid restaurants, travel, social events, school, work, or other activities because they are worried about what might happen.

A GI psychologist can teach strategies for managing anticipatory anxiety and help patients gradually rebuild confidence in participating in meaningful activities—while continuing to follow appropriate medical precautions.

3. Developing coping skills for symptom flares

Depending on the individual’s needs, treatment may include practical strategies such as:

diaphragmatic breathing
relaxation training
cognitive behavioral strategies
mindfulness-based approaches
gut-directed hypnotherapy
coping strategies for pain, nausea, or GI discomfort
strategies for managing symptom-related worry
sleep and daily-routine support
reducing excessive body checking or reassurance seeking when appropriate

These approaches are not intended to “cure” MCAS. Instead, they may help patients manage the impact of GI symptoms and improve functioning and quality of life as one part of comprehensive care (Keefer et al., 2022).

4. Supporting a healthy relationship with food

Food can become particularly complicated when someone has experienced symptoms after eating.

A person may begin eliminating foods one by one, eating an increasingly narrow range of foods, or feeling afraid to eat because they do not know what might trigger symptoms.

When medically appropriate, a multidisciplinary team can help distinguish between medically necessary dietary precautions and patterns of restriction that may be driven by fear or uncertainty.

A GI psychologist can collaborate with a GI dietitian and medical providers to support a healthy relationship with food, reduce food-related anxiety, and address the emotional burden of managing a chronic GI condition.

For children and adolescents, this collaboration can be especially important because unnecessary or excessive dietary restriction can affect nutrition, growth, social experiences, and family mealtimes.

5. Helping parents support children without increasing fear

Parents naturally want to protect their child from uncomfortable or potentially dangerous symptoms.

When a child is frequently worried about reactions, however, parents may find themselves repeatedly checking symptoms, modifying activities, asking whether the child feels okay, or avoiding situations that could potentially cause discomfort.

These responses are understandable—and sometimes medically necessary. When appropriate, a GI psychologist can help families find a balance between safety and confidence.

For example, parents might practice language such as:

“Let’s follow the plan your medical team gave us. Your body may have uncomfortable sensations, and we know what steps to take if symptoms happen.”

This approach validates the child’s experience while communicating confidence, predictability, and support.

Why Can a Multidisciplinary Team Be Helpful?

Because symptoms associated with mast-cell disorders can involve multiple body systems, care may benefit from multiple perspectives.

Depending on the individual’s needs, a care team might include:

Allergist/immunologist: Evaluates suspected mast-cell disorders, helps clarify diagnostic questions, monitors symptoms, and manages medical treatment and emergency planning when indicated.
Gastroenterologist: Evaluates GI symptoms and considers other gastrointestinal conditions that may mimic or coexist with mast-cell-related symptoms.
GI dietitian: Helps address nutrition, dietary adequacy, food-related concerns, and medically appropriate dietary modifications.
GI psychologist: Addresses the gut-brain connection, symptom-related anxiety, coping, behavioral patterns, quality of life, and adjustment to chronic GI symptoms.
Primary care provider: Helps coordinate overall medical care and monitor the broader health picture.

The goal is not for every patient to see every specialist. Instead, the goal is to build the right team for the individual patient.

Collaborative, empathic care and appropriate non-medication approaches are important components of managing persistent GI symptoms, particularly when symptoms involve disorders of gut-brain interaction (Keefer et al., 2021).

Practical Tips for Patients

If you are exploring whether MCAS may be contributing to your symptoms, consider keeping a simple record of:

What symptoms occur
When symptoms occur
How long episodes last
Which body systems are affected
Potential triggers or circumstances surrounding an episode
Medications or treatments used
What helped
Questions you want to discuss with your medical team

Bring this information to your appointments rather than trying to diagnose yourself based on symptom lists online.

It may also be helpful to ask your healthcare provider:

“What other conditions could explain these symptoms?”
“What testing is appropriate for me?”
“If MCAS is suspected, how will we confirm or rule it out?”
“What should I do during an acute episode?”
“What symptoms would require urgent or emergency care?”
“Would a GI dietitian or GI psychologist be helpful as part of my care?”

Practical Tips for Caregivers

For caregivers supporting a child with suspected or diagnosed MCAS:

Take your child’s symptoms seriously without assuming every sensation signals danger.
Follow the medical team’s emergency and medication plan.
Keep routines as predictable as possible.
Avoid making food or symptoms the sole focus of family conversations.
Encourage age-appropriate participation in school, activities, and social experiences when medically safe.
Ask your child’s care team how to balance appropriate precautions with independence.
Consider behavioral health support when worry, avoidance, or symptom monitoring begins interfering with everyday life.

Practical Tips for Providers

For healthcare professionals, patients with complex GI and mast-cell-related symptoms may benefit from language that validates the patient’s experience while maintaining diagnostic rigor.

Consider:

Acknowledge that the patient’s symptoms are real and distressing.
Explain what has been ruled out and what remains under evaluation.
Avoid prematurely attributing unexplained symptoms solely to anxiety.
At the same time, avoid assuming that every nonspecific symptom is caused by mast-cell activation.
Coordinate care across specialties when symptoms span multiple systems.
Consider referral to GI psychology when symptom-related anxiety, avoidance, hypervigilance, coping difficulties, or reduced quality of life become clinically relevant.
Use patient-friendly explanations of the gut-brain connection.

A collaborative relationship can help patients feel heard while also supporting appropriate medical evaluation and treatment.

A Note About Emergency Symptoms

Some mast-cell reactions can involve anaphylaxis, a serious and potentially life-threatening allergic reaction.

Symptoms such as difficulty breathing, throat swelling, significant swelling, fainting, or severe low blood pressure require urgent medical attention. If you have a history of severe allergic reactions or anaphylaxis, follow the emergency plan provided by your medical team, including use of prescribed epinephrine when indicated.

This article is for educational purposes and is not a substitute for individualized medical evaluation or emergency care.

Key Takeaway: Caring for the Whole Person

MCAS is a complex condition that can affect multiple body systems—and living with unpredictable symptoms can affect much more than physical health.

A thoughtful treatment plan may include medical evaluation and treatment alongside nutrition support, behavioral strategies, and attention to the gut-brain connection.

For patients and families, one of the most important takeaways is this:

You do not have to choose between taking physical symptoms seriously and addressing the emotional and nervous-system impact of those symptoms. Both can be important parts of comprehensive care.

A GI psychologist can be one member of a larger care team, helping patients understand their gut-brain connection, develop coping skills, reduce symptom-related fear and avoidance, and reconnect with daily activities and quality of life—while continuing appropriate medical care.

Interested in Learning More?

If you are looking for additional education and support related to GI health and the gut-brain connection, explore our patient resources, explore free resources, schedule a free 15-minute phone consultation, or refer a patient to learn how GI-focused behavioral health can help.

References

American Gastroenterological Association. (2021). Management of chronic gastrointestinal pain in disorders of gut-brain interaction: Clinical practice update. Gastroenterology.

Hamilton, M. J. (2024). Mast cell activation syndrome and gut dysfunction: Diagnosis and management. Current Gastroenterology Reports, 26, 1–8.

Keefer, L., Ballou, S. K., Drossman, D. A., Ringstrom, G., Elsenbruch, S., & Ljótsson, B. (2022). A Rome Working Team report on brain-gut behavior therapies for disorders of gut-brain interaction. Gastroenterology, 162(1), 300–315.

Valent, P., Akin, C., Bonadonna, P., Brockow, K., Broesby-Olsen, S., Escribano, L., Hartmann, K., Lange, M., Niedoszytko, M., Nedoszytko, B., Sperr, W. R., Triggiani, M., van Anrooij, B., & Horny, H.-P. (2019). Mast cell activation syndrome: Importance of consensus criteria and call for research. Journal of Allergy and Clinical Immunology, 143(3), 944–949.

Valent, P., Akin, C., Hartmann, K., Nilsson, G., Reiter, A., Hermine, O., & Arock, M. (2020). Diagnosis, classification and management of mast cell activation syndromes (MCAS) in the era of personalized medicine. International Journal of Molecular Sciences, 21(23), 9030.

American Academy of Allergy, Asthma & Immunology. (2026). Mast cell activation syndrome (MCAS).