What is MCAS?

Mast Cell Activation Syndrome occurs when mast cells (immune cells found throughout the body) release histamine and other inflammatory chemicals inappropriately or excessively, even without a true allergic trigger. Because mast cells are present in the skin, gut, respiratory tract, nervous system and cardiovascular system, MCAS symptoms can show up almost anywhere in the body and often don't follow a predictable pattern.

This is part of what makes MCAS so difficult to diagnose. Many people are told their symptoms are anxiety, or unexplained allergies, after years of normal standard test results.

Common MCAS symptoms

• Flushing, hives, or unexplained skin rashes. Itching without a visible rash, reactions to foods, medications, fragrances or supplements that seem to change or worsen over time.

• Digestive symptoms such as bloating, diarrhea, abdominal pain

• Lightheadedness, rapid heart rate or blood pressure changes

• Brain fog, anxiety or a sense of nervous system dysregulation

• Nasal congestion, throat tightness or shortness of breath without a clear allergic cause

• Symptoms that seem to be triggered by heat, stress, exercise or hormonal changes

How I Assess MCAS

MCAS is a clinical diagnosis built from pattern recognition as well as lab values. I take a detailed history of your symptoms, triggers, timeline and any prior testing or treatments you've tried.

My Approach to Treatment

MCAS treatment is about identifying and addressing the underlying drivers while stabilizing symptoms in the meantime. My approach typically includes:

• Mast cell stabilization: targeted botanical and nutraceutical support to reduce reactivity while we investigate root causes

• Dietary strategy: a personalized low-histamine approach

• Identifying root triggers: mold exposure, chronic infections, gut imbalances (including SIBO, dysbiosis and H. pylori) and nervous system dysregulation

• Nervous system support: stress and nervous system dysregulation can directly worsen mast cell reactivity

Frequently Asked Questions

What is the difference between MCAS and Histamine Intolerance?

Histamine intolerance relates to the body's capacity to break down histamine (often from diet), while MCAS involves mast cells releasing a broader range of inflammatory mediators, not histamine alone. Many people have features of both and the distinction is part of what we work through together.

Do I need a specialist diagnosis before seeing you?

No. Many of my patients come to me without a formal diagnosis, often after months or years of unexplained symptoms. Part of my role is helping you understand what's actually going on.

Can MCAS be related to mold exposure?

Yes, mold and mycotoxin exposure is one of the more common underlying triggers I see in patients with MCAS. If this applies to you, we'll look at this together.

Can hormonal changes trigger MCAS symptoms?

Hormones and mast cells have a bidirectional relationship. Estrogen in particular can directly activate mast cells, which is why many women notice that MCAS symptoms flare in connection with their menstrual cycle, in perimenopause or even due to bioidentical hormones. Testosterone generally has a stabilizing effect on mast cells, but low testosterone or elevated estrogen can contribute to increased mast cell reactivity and worsening symptoms.