Is It Really Anxiety? Or Could It Be MCAS?
Most people have never heard of mast cell activation syndrome (MCAS)—yet research suggests that as many as 1 in 6 people may be living with it.
Even more surprising? MCAS is often mistaken for a mental health issue, especially in people who present with symptoms like brain fog, anxiety, insomnia, or emotional dysregulation.
Here’s what MCAS can actually look like:
Brain fog that feels like dissociation or depression
Irritability or mood swings with no obvious trigger
Sensitivity to light, sound, smell, or texture
Insomnia, night-time panic, or waking up with a racing heart
Shortness of breath, a lump in your throat, or feeling like you cannot relax
Unrelenting fatigue or muscle pain
Social withdrawal due to unpredictable symptoms
Nausea, abdominal pain, or unexplained gastrointestinal (GI) distress
Lack of positive response to psychiatric medications or psychotherapy
These symptoms often get written off as anxiety, trauma responses, attention-deficit/hyperactivity disorder (ADHD), or mood disorders like depression. And sometimes, those conditions are also present. But for people with MCAS, there is a cause for these symptoms: immune system dysfunction.
What Is MCAS, Really?
In MCAS, mast cells—a type of immune cell—release excessive chemicals like histamine into the body. This can affect nearly every organ system, leading to a mix of neurological, cardiovascular, gastrointestinal, and skin symptoms.
The trouble is, MCAS doesn’t always follow a clear pattern. Symptoms may come and go, or worsen in response to heat, stress, foods, medications, or hormones. That makes it hard to identify—and even easier to misdiagnose.
Why MCAS Is So Often Confused with Mental Health Conditions
MCAS can cause:
Low mood or depression
Restlessness or irritability
Panic attacks or a racing mind
Sleep disturbances
Brain fog and memory problems
While these look like psychiatric symptoms, they stem from immune dysregulation. That’s why traditional mental health treatments often fall short for people with MCAS.
The Problem with Missed Diagnoses
When MCAS goes unrecognized, people may spend years:
Trying multiple medications that do not help
Internalizing their symptoms as personal failures
Wondering if their distress is “all in their head”
Being dismissed or misdiagnosed in clinical settings
Worse yet, symptoms may continue to progress if the cause of them—mast cell dysfunction—is never addressed.
Getting the Right Diagnosis and Treatment
MCAS can be diagnosed—but only if a healthcare provider knows how to look for it. This often involves:
Tracking symptom patterns over time
Identifying triggers (like heat, stress, or certain foods)
Lab testing for markers of mast cell activity (like histamine or tryptase), but recognizing that lab testing for MCAS is flawed and can easily miss the diagnosis
Trialing medications such as mast cell stabilizers, antihistamines, or low-histamine diets for symptom relief
Treatment is highly individualized—but when MCAS is correctly identified, many people see significant relief.
Why Awareness Matters
MCAS is still underdiagnosed and misunderstood, despite growing recognition in specialties like allergy, immunology, and functional medicine.
Raising awareness means fewer people are told their symptoms are caused by a mental health condition. It means more people get access to the right care. And it means those struggling with unexplained symptoms might finally feel validated—and start to feel better.
Could MCAS Be the Missing Piece?
If you have been told your symptoms are psychiatric but you just don’t feel like that’s the whole story, MCAS might be worth exploring. No one should feel dismissed for symptoms that do not fit neatly in a box.
It is time we stop ignoring the immune system’s role in emotional and physical health—and start asking better questions about what is really going on.
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PMID: 38003876; PMID: 32328892
Disclaimer: This blog post is for informational purposes only and shall not be construed as behavioral health or medical advice. It is not intended or implied to supplement or replace treatment, advice, and/or diagnosis from your own qualified healthcare provider.