Is It Allergies… or MCAS?
Why Your “Allergy” Symptoms Might Be a Sign of Mast Cell Activation
We’ve all been there—sneezing, itchy skin, brain fog, food reactions—blaming it on seasonal allergies or a “sensitive system.” But what if it’s not just allergies at all? What if your immune system is stuck in overdrive?
As a functional medicine practitioner, I’ve been seeing a rise in complex, chronic cases where the usual antihistamines and nasal sprays don’t cut it. More often than not, the real culprit is Mast Cell Activation Syndrome (MCAS)—a hidden condition that’s finally getting the attention it deserves.
What Is MCAS?
MCAS is a chronic, multisystem condition where mast cells (a type of immune cell) release chemical mediators like histamine inappropriately and excessively, triggering widespread inflammation and symptoms across nearly every body system.
Common Symptoms Include:
Skin: Flushing, itching, hives, rashes, swelling, dermatographia
Gut: Bloating, nausea, food sensitivities, IBS-like symptoms
Cardiovascular: Heart palpitations, dizziness upon standing (often overlapping with POTS), chest tightness
Respiratory: Congestion, wheezing, asthma-like symptoms
Neurological: Brain fog, migraines, anxiety, insomnia, light/sound sensitivity
Other Signs: Fatigue, menstrual irregularities, heat/cold intolerance, even anaphylactoid reactions without a clear allergen
Is It in Your Genes?
Certain genetic variants can make it harder for your body to break down histamine or regulate mast cell activity. The most common ones we see:
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KIT mutations – Linked to abnormal mast cell behavior
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MTHFR – Impaired methylation = slower detox + more histamine
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DAO and HNMT – The body’s histamine clean-up crew; if these underperform, symptoms build
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HLA-DRB1 – Connected to autoimmunity and hyper-reactivity
Functional genomic testing (like DFH’s Genomics Spotlight) can help you uncover these patterns.
Common Triggers of MCAS & Histamine Overload
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Environmental: Mold, VOCs, pollen, EMFs
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Chemical: Fragrances, preservatives, certain medications
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Biological: Lyme, Candida, EBV, parasites
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Dietary: Aged cheeses, wine, leftovers, additives, gluten
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Stress: Psychological trauma, overtraining, chronic illness
How to Calm the Storm – A Functional Medicine Approach
Healing starts by addressing the root.
Key Areas to Focus On:
✔️ Identify and reduce exposure to triggers (e.g., mold, gluten, fragrances)
✔️ Rebuild gut lining and lower inflammation
✔️ Support methylation and detox pathways
✔️ Use mast cell stabilizers and histamine-lowering tools
My Go-To Products to Support Histamine & MCAS Naturally
Find these items in my Supplement Store →
Hista-Eze Quercetin + Vitamin C, Nettles – A powerful natural mast cell stabilizer
DAO Enzymes – Support the breakdown of dietary histamine
Magnesium Glycinate – Calms the nervous system and promotes detox
Find these curated items in my Amazon Wellness Store →
Air Purifiers + VOC-Free Pillows – Reduce home-based triggers
EMF-Blocking Phone Cases + Blue Light Glasses – Less stress = less histamine
Final Thoughts
If you’ve been stuck in a loop of “allergies,” skin issues, fatigue, or weird food reactions—and nothing seems to help—it’s time to zoom out. Your immune system may be trying to tell you that something deeper is going on.
Calming the Chaos: How We Actually Heal MCAS
Once mast cells are triggered, they don’t just calm down on their own—you have to remove what lit the fire in the first place.
That means uncovering and addressing the underlying root causes:
✔️ Gut issues
✔️ Food sensitivities and allergies
✔️ Hidden infections (like Candida, parasites, or EBV)
✔️ Environmental or chemical triggers
Then—and only then—can we begin to retrain and rebalance the immune system so it stops overreacting to everything.
It’s not always simple. It can be layered and complex.
But this is exactly the kind of root-cause work we do inside my program, ROOT Rx.
We don’t just chase symptoms—we rebuild your body from the inside out.
Click Here to BOOK a Free Consult!
Happy Healing!
xo,
Dr. Sheena
