Could Mast Cell Activation Be Behind Your Symptoms

Hi Friend

Mast Cell Activation Syndrome (MCAS) is increasingly recognised as part of the puzzle in chronic conditions like fibromyalgia, ME/CFS, long COVID, Ehlers-Danlos syndrome, and POTS (Postural Orthostatic Tachycardia Syndrome). Yet, many people live with its symptoms for years before it is considered.

Let’s break it down — what MCAS is, how it can affect you, and what you can do about it.

🧬 What Are Mast Cells and Why Do They Matter?

Mast cells are part of your immune system — like the body’s early warning system. They sit in tissues that interact with the outside world:

• Skin

• Gut lining

• Respiratory tract

• Blood vessels

They store and release over 200 chemicals (called mediators), such as:

• Histamine — causes itching, flushing, hives, and swelling

• Tryptase — involved in tissue repair, but can contribute to inflammation

• Prostaglandins and leukotrienes — contribute to pain, swelling, gut issues

• Cytokines — drive immune responses

In MCAS, mast cells release these mediators inappropriately or excessively in response to triggers — or sometimes with no clear trigger at all.

⚠️ What Are the Symptoms of MCAS?

MCAS is a "great mimicker" because it can affect almost every system. People often experience:

Skin:

• Flushing, hives, itching, easy bruising

• Swelling of lips, eyes, or tongue (angioedema)

Gut:

• Nausea, bloating, cramping, diarrhoea, reflux

• Food sensitivities

Respiratory:

• Nasal congestion, asthma-like wheezing, shortness of breath

Cardiovascular:

• Palpitations, lightheadedness, fainting

• Low blood pressure during flares

Neurological:

• Brain fog, headaches, migraines

• Anxiety-like sensations (often driven by histamine release)

Other:

• Joint and muscle pain (especially in those with Ehlers-Danlos or fibromyalgia)

• Fatigue, temperature sensitivity

🌱 Common Triggers for MCAS Flares

People with MCAS may react to:
⚡ Heat or cold
⚡ Stress (emotional or physical)
⚡ Infections or injuries
⚡ Alcohol
⚡ Certain medications (opioids, NSAIDs, contrast dyes, some anaesthetics)
⚡ High-histamine foods (see diet tips below)

🩺 How Is MCAS Diagnosed?

There’s no single test for MCAS. Diagnosis usually combines:
1️⃣ History of recurrent multisystem symptoms suggestive of mast cell mediator release
2️⃣ Evidence of abnormal mediator levels (sometimes elevated tryptase, prostaglandin D2, urinary histamine metabolites — often normal between flares)
3️⃣ Symptom improvement with treatments that block or stabilise mast cells

👉 Tip: Keeping a detailed symptom and food trigger diary can be crucial in identifying patterns.

💊 Management Options for MCAS

🔹 Medications

• H1 antihistamines: cetirizine, loratadine, fexofenadine (for itching, flushing, hives)

• H2 antihistamines: famotidine, ranitidine (for reflux, gut symptoms)

• Mast cell stabilisers: cromolyn sodium (oral), ketotifen (oral, sometimes topical for eyes)

• Leukotriene inhibitors: montelukast

• Low-dose aspirin (only in some, under medical guidance)

⚠️ Always start low and go slow — people with MCAS can be sensitive to medications.

🔹 Lifestyle Strategies

• Low-histamine / mast-cell-friendly diet (see below)

• Stress management (e.g. meditation, gentle yoga)

• Avoid extreme temperatures

• Gentle exercise pacing

🍽️ Low-Histamine Diet: A Starting Point

Histamine builds up in food over time, so fresh is best.

✅ Safer options:

• Freshly cooked chicken, turkey, white fish

• Rice, quinoa, oats

• Most fresh vegetables (except tomato, aubergine, spinach, avocado)

• Fresh fruits like apples, pears, blueberries (avoid citrus at first)

• Olive oil, coconut oil

❌ Common triggers to avoid:

• Aged cheese

• Cured / smoked meats (salami, ham)

• Alcohol (especially wine, beer)

• Vinegar, pickles, soy sauce

• Fermented foods (yogurt, kefir, sauerkraut)

• Leftovers kept too long

🛒 Example Shopping List (Low-Histamine Friendly)

• Fresh chicken breast or turkey

• Fresh white fish (cod, haddock)

• Courgettes, carrots, green beans, lettuce, cucumber

• Apples, pears, blueberries

• Rice, quinoa, oat cakes

• Olive oil, coconut oil

• Herbal teas (rooibos, chamomile — test tolerance)

👉 Tip: Freeze portions of cooked meat or fish straight away if not eating immediately.

🧠 MCAS and Related Conditions

Research suggests MCAS may overlap with:

• Fibromyalgia: Some people with fibromyalgia have elevated mast cell markers in muscle tissues.

• Long COVID: Emerging studies (Weinstock 2021, Afrin 2020) link long COVID symptoms to mast cell activation.

• POTS / EDS: High rates of MCAS in people with these conditions point to shared connective tissue and autonomic system vulnerabilities.

📝 Final Thoughts

MCAS can feel overwhelming — but understanding your body’s triggers and responses is the first step toward managing it. If you suspect MCAS, work with a knowledgeable clinician, and consider tracking your symptoms to spot patterns. Next week we will look into management options in more detail

I Help alot of people with MCAS, if you are interested to find out more please reply and I can help, or you can book a appt with me directly using the link below:

Best Wishes

Dr Ahmed