Could Your Unexplained Symptoms Be Mast Cell Activation Syndrome (MCAS)? 

By: Physicians Preference RX

“I’m allergic to everything.” 

“I feel awful in general.” 

“My doctor says it’s all in my head.” 

“I have hives, and I have no idea why.” 

“I get migraines with my period.” 

If any of these statements feel familiar, you are not alone, and your symptoms are certainly not imaginary. You may be dealing with Mast Cell Activation Syndrome (MCAS), a complex, multi-system condition that is far more common than most people (and many doctors) realize. Some researchers estimate it may affect roughly 17% of the general population and an even higher percentage of people with obesity.¹ Symptoms often begin in childhood and continue into adulthood, yet the average person goes undiagnosed for decades.² 

You have probably been told your labs look “perfect,” that you are the “picture of health,” or that anxiety, depression, or stress must be the root cause. That experience leaves many people frustrated, exhausted, and without hope.  

MCAS is real. Mast cells can be calmed. When you recognize the condition early and address it, many people experience meaningful improvement and restored hope. 

What Are Mast Cells and Why Do They Go Haywire? 

Mast cells are a type of innate immune white blood cell found in nearly every tissue in the body. They are especially concentrated in the body’s first lines of defense: the skin, gastrointestinal tract, lungs, nose, and eyes. They also exist in the nervous system, bones, and elsewhere. 

Their job is protective. When they detect a threat, they release chemical mediators (including histamine, tryptase, prostaglandins, and many others) that help fight infection, regulate inflammation, and maintain the blood-brain barrier. But when mast cells become chronically over-responsive, they react to ordinary everyday exposures instead of just real dangers. The result is widespread, fluctuating symptoms that can affect virtually every organ system. 

There are more than 200 different types of receptors on mast cells. When these cells remain in a heightened state of alert, the entire body can feel as if it is under constant attack. 

What Triggers Mast Cells? 

Almost anything can activate over-sensitive mast cells. Common triggers include: 

Foods and beverages (especially high-histamine items)  

Examples: Red wine, aged cheeses, avocados, spinach, tomatoes, fermented or pickled foods, leftovers, and foods cooked slowly in a Crock-Pot 

Medications and supplements 

Examples: Tablets or capsules that contain dyes, artificial colors, flavors, binders, fillers, or preservatives. Even “natural” supplements can trigger reactions if they contain unnecessary additives. 

Environmental allergens, mold, and mycotoxins  

Examples: Indoor mold (even low levels others may not notice), mycotoxins from water-damaged buildings, pollen, dust mites, pet dander, and strong chemical smells or fragrances 

Stress (physical or emotional) and neurotransmitters  

Examples: Acute emotional stress, chronic anxiety, lack of sleep, intense exercise, or the body’s own stress hormones (cortisol and adrenaline surges) 

Hormones 

Examples: Estrogen fluctuations around the menstrual cycle, ovulation, pregnancy, or perimenopause. Many women notice flares timed with their period or hormone shifts. 

Injuries, infections, and pathogens  

Examples: Viral illnesses (including residual effects after infections), bacterial or parasitic gut infections, physical trauma, surgery, or dental work. 

Temperature changes, exercise, and pressure on the skin 

Examples: Sudden heat or cold, hot showers, sweating, friction from tight clothing, or dermatographia (skin that welts and remains red even when lightly scratched) 

Invisible factors such as electromagnetic fields (EMF) and Wi-Fi 

Examples: Prolonged exposure to cell phones, Wi-Fi routers, or other electronic devices. Some people with MCAS show increased symptoms with these exposures, while others notice little to no effect. Sensitivity varies widely from person to person. 

Anything that touches the skin or is inhaled  

Examples: Lotions, soaps, laundry detergents, essential oils, cigarette smoke, vehicle exhaust, or airborne chemicals. 

These triggers often stack on top of one another. Foods that were previously tolerated can suddenly cause symptoms when stress, hormones, or mold exposure are also high. Tracking personal patterns in a simple symptom-and-exposure journal is a helpful first step toward clarity.  

Common Symptoms of MCAS 

Because mast cells are everywhere, symptoms vary widely and often wax and wane. They frequently involve two or more body systems at once. Here is a practical overview organized by system:³ 

Body System	Common Symptoms
Skin	Unexplained hives, itching (with or without rash), flushing, dermatographias (“skin writing”), poor wound healing, temperature intolerance
Gastrointestinal	Abdominal pain/cramping, nausea, diarrhea or alternating constipation, bloating, early satiety, reflux, food sensitivities
Cardiovascular	Fluctuating blood pressure, rapid heart rate or palpitations, dizziness, lightheadedness, near-fainting or fainting
Neurologic / Cognitive	Brain fog, memory or concentration difficulties, headaches or migraines (including menstrual migraines), anxiety, insomnia, fatigue/malaise
Respiratory	Nasal congestion, runny nose, wheezing, shortness of breath, frequent “allergies” or infections
General / Other	Night sweats (especially on the back), hot flashes, dramatic weight changes, low-grade fevers or feeling cold, muscle/joint pain, sensitivity to medications and supplements

This list only scratches the surface. Many people also experience enlarged lymph nodes, vision or hearing changes, and an intense sense of “feeling awful in general” despite normal conventional testing. 

Histamine intolerance is closely linked. Histamine released from mast cells contributes to hives, congestion, post-meal accelerated heartbeat, migraines, insomnia, and panic-like symptoms. For many people, MCAS is the primary driver of histamine intolerance. Conditions that can worsen histamine issues include gluten sensitivity, estrogen dominance, leaky gut, gut infections, mold exposure, and EMF sensitivity. 

Why Is MCAS So Often Missed? 

Most healthcare providers receive little to no training on MCAS. Standard blood work and imaging are often normal because the problem isn’t structural damage or a single lab abnormality; it is dysregulated immune signaling. When doctors cannot find an “organic” explanation, they may attribute symptoms to stress, anxiety, or somatization (a term sometimes used when physical symptoms cannot yet be explained by standard tests, leading providers to conclude the symptoms are influenced by emotional or stress-related factors). Patients then feel dismissed and stop seeking answers. 

Diagnostic delays are common. In one large series, the median time from symptom onset to diagnosis was 30 years.² Women are diagnosed more often than men, and symptoms can worsen around hormonal shifts (puberty, menstrual cycles, pregnancy, perimenopause). 

Common Contributors 

While every person’s picture is unique, these factors frequently keep mast cells overactivated:⁴ 

• Food triggers (especially high-histamine foods) 

• Hormone imbalances (particularly estrogen dominance) 

• Chronic infections and toxicity (including mold/mycotoxins) 

• Ongoing stress or early-life trauma 

• Genetic predispositions 

• Tissue oxygen deficiency (hypoxia) 

• Nutritional deficiencies 

There Is Real Hope: How MCAS Is Managed 

The goal of treatment is not to eliminate mast cells (they are necessary) but to reduce unnecessary activation, block excessive mediator release, and strengthen overall resilience. With a layered, individualized approach, you are expected to continually improve with time. 

1. Identify and reduce triggers 

Keep a simple symptom-and-exposure diary for a few weeks. Note foods, environments, stress levels, menstrual cycle phase, sleep, and symptoms. This information is extremely valuable for your doctor and your own personal tracking of symptoms. 

2. Low-Histamine Diet Considerations 

Many people with MCAS notice that high-histamine foods, or histamine “liberating” foods, worsen symptoms such as flushing, hives, headaches, gut distress, or heart palpitations. A temporary low-histamine trial can help calm the system while other lifestyle changes are implemented. The key principles are food freshness and individual tolerance; histamine levels rise the longer food sits, even in the refrigerator. 

Foods that are often higher in histamine or more likely to trigger symptoms (limit or avoid during a trial): 

• Aged or fermented foods: aged cheeses, yogurt, kefir, sauerkraut, kimchi, kombucha, soy sauce, miso, vinegar 

• Cured, smoked, or processed meats: bacon, salami, deli meats, hot dogs, sausages 

• Leftovers and slow-cooked foods (Crockpot meals) 

• Certain fruits and vegetables: avocados, spinach, tomatoes, eggplant, citrus, strawberries, bananas, pineapple 

• Alcohol (especially red wine and beer) 

• Canned or smoked fish, shellfish 

• Chocolate and cocoa 

Foods that are generally better tolerated (focus on these): 

• Freshly cooked meats and poultry (chicken, turkey, beef) eaten soon after cooking, or frozen immediately to be reheated and eaten at a later time 

• Most fresh vegetables: zucchini, carrots, broccoli, cauliflower, cucumber, lettuce, sweet potatoes, asparagus 

• Fresh fruits: apples, pears, blueberries, blackberries, melon, mango (in moderation) 

• Grains: rice, quinoa, oats, millet 

• Healthy fats: olive oil, coconut oil, ghee 

• Fresh herbs and simple seasonings (basil, oregano, rosemary, salt, pepper) 

• Herbal teas (chamomile, peppermint, etc.) 

Helpful hints: 

• Cook and eat food as fresh as possible. Freeze leftovers right away if you plan to eat them later. 

• Start simply—many people begin by removing the biggest offenders (leftovers, aged/fermented foods, alcohol, and cured meats) for 2–4 weeks to notice how they feel. 

• This is not meant to be a permanent, highly restrictive diet. The goal is to lower the histamine load while you address root triggers and stabilize mast cells. Work with a knowledgeable practitioner to systematically reintroduce foods and avoid unnecessary long-term restrictions. 

• Individual reactions differ widely. What bothers one person may be fine for another. 

3. Medications and stabilizers 

Many people benefit from: 

• H1 antihistamines (non-sedating options such as loratadine, cetirizine, or fexofenadine) 

• H2 antihistamines (such as famotidine) — these help both gut and systemic symptoms 

• Mast-cell stabilizers (cromolyn sodium, ketotifen, amlexanox) 

• Leukotriene modifiers in some cases 

• Other targeted supports for detoxification pathways, inflammation, or hormone balance 

Because people with MCAS are often exquisitely sensitive to inactive ingredients (dyes, fillers, binders, artificial flavors), pure compounded medications free of unnecessary additives can have a significant impact. Starting low and going slow is essential. 

4. Support the bigger picture 

Gentle detoxification (when the body can tolerate it), hormone balancing, gut repair, stress reduction, and treating any underlying infections or mold exposure are important complementary pieces. Sleep, nervous system regulation, and avoiding unnecessary chemical exposures also help. 

Improvement is usually gradual. Many people notice better energy, fewer flares, clearer thinking, and greater tolerance of foods and environments over months of consistent management. Mast cells are not the enemy; they simply need to be brought back into appropriate regulation. 

How Physicians Preference Pharmacy Can Help 

Many people with MCAS are highly sensitive to the inactive ingredients found in commercial medications: dyes, artificial colors, flavors, fillers, binders, and preservatives. These additives can sometimes trigger or worsen symptoms, even when the active ingredient itself is helpful. 

Physicians Preference Pharmacy is a PCAB-accredited compounding pharmacy that works closely with healthcare providers to prepare customized medications according to the prescriber’s exact specifications. When appropriate, we can make formulations without dyes, unnecessary fillers, or other potentially bothersome inactive ingredients, offering a cleaner option for those who are more sensitive. 

We compound a range of medications commonly used to support people with MCAS, including: 

• Famotidine capsules 

• Loratadine capsules 

• Diphenhydramine slow-release capsules 

• Brompheniramine slow-release capsules 

• Chlorpheniramine slow-release capsules 

• Hydroxyzine slow-release and immediate-release capsules 

• Ketotifen capsules 

• Amlexanox capsules 

• Cromolyn sodium capsules 

• Sirolimus capsules 

• Low Dose Naltrexone capsules 

• Progesterone slow-release capsules 

Here’s a simple overview of how these medications are often used: 

Medication	Type	Main Benefit in MCAS
Famotidine	H2 antihistamine	Helps with stomach acid, GI symptoms, and some systemic histamine effects
Loratadine	Non-sedating H1 antihistamine	Reduces itching, hives, flushing, and allergic-type symptoms without drowsiness
Diphenhydramine (slow-release)	Sedating H1 antihistamine	Helps with itching, hives, and can support sleep; longer-lasting coverage
Brompheniramine (slow-release)	Sedating H1 antihistamine	Helps control allergic symptoms and itching with extended relief
Chlorpheniramine (slow-release)	Sedating H1 antihistamine	Used for itching, hives, and allergic symptoms; longer-lasting form
Hydroxyzine	Sedating H1 antihistamine	Especially helpful for intense itching, hives, and anxiety-related symptoms
Ketotifen	H1 antihistamine + mast cell stabilizer	Helps both relieve symptoms and calm overactive mast cells

If your healthcare provider determines that a compounded medication may be beneficial as part of your treatment plan, our pharmacists are available to collaborate with them to help meet your individual needs. We are happy to answer questions from both you and your providers. 

Call our pharmacy team at 281-828-9088 to learn more. 

You Are Not Alone, and You Are Not “Crazy” 

If you have spent years feeling dismissed, take this to heart: your symptoms have a biological explanation. MCAS is increasingly recognized, and knowledgeable clinicians and compounding pharmacists exist who understand how to approach it strategically. Recovery is possible. People who once believed they would never feel well again often report meaningful gains in quality of life once the right combination of trigger reduction, stabilization, and support is in place. 

Start by sharing this information with your provider who is open to learning. Ask for an evaluation for mast-cell issues. Keep advocating for yourself. And know that pure, individualized, compounded options are available for those who need them. 

You have already survived the hardest part, living with unexplained, multi-system symptoms for so long. With the right recognition and support, the road ahead can look very different. 

Professionally reviewed by Bryana Burken, PharmD, RPh

References 

1. Molderings GJ, et al. Mast cell activation disease: a concise practical guide for diagnostic workup and therapeutic options. J Hematol Oncol. 2011. 

2. Afrin LB, Self S, Menk J, Lazarchick J. Characterization of Mast Cell Activation Syndrome. Am J Med Sci. 2017;353(3):207-215. 

3. Afrin LB. Never Bet Against Occam: Mast Cell Activation Disease and the Modern Epidemics of Chronic Illness and Medical Complexity. 2016. 

4. Physicians Preference Pharmacy. “Is It MCAS or Is It All in Your Head?” Patient Newsletter, Q2 2023. 

5. Theoharides TC, et al. Mast cells and inflammation. Biochim Biophys Acta. 2012. 

6. Valent P, et al. Definitions, criteria and global classification of mast cell disorders with special reference to mast cell activation syndromes: a consensus proposal. Int Arch Allergy Immunol. 2012. 

7. Weinstock LB, et al. Mast cell activation syndrome: a primer for the gastroenterologist. Dig Dis Sci. 2021. 

8. Campbell B. The 4-Phase Histamine Reset Plan. 

9. O’Hara B. Mast Cell 360 resources on MCAS triggers and management. 

10. Akin C. Mast cell activation syndromes. J Allergy Clin Immunol. 2017.