Mast Cells and Chemical Intolerance

Updated: Mar 24

Chemicals and toxins are everywhere: in our conventional cleaning, body, and beauty products; paint, plastics, our air, and so on. Yet, most people don’t experience severe reactions when exposed to these chemicals. For others, even washing their hair with conventional shampoo or breathing in tobacco smoke can lead to severe health issues.

Chemical intolerance or multiple chemical sensitivity are characterized by widespread, multi-system symptoms caused by low-level exposure and toxins. Symptoms of chemical intolerance are very similar to mast cell activation syndrome (MCAS). We also know that chemicals and toxins are one of the main triggers of your mast cells, causing histamine and other mediator release.


You may wonder if there is a connection between mast cells and chemical intolerance. A new exciting study has discovered that MCAS may increase the risk of chemical intolerance and chemical exposure may drive both conditions. In this article, I want to discuss the connection between mast cells and chemical intolerance.


What Is Chemical Intolerance?

As you see, chemicals can trigger mast cell activation. But can mast cell activation and chemical intolerance be linked? Before we get into this, let’s talk about chemical intolerance.

Chemical intolerance (CI) is a chronic condition. Chemical intolerance may also be referred to as multiple chemical sensitivity (MCS). It is characterized by a complex list of recurring, chronic, and often severe symptoms caused by low-level exposure to chemicals that are unproblematic for most people. Symptoms may affect multiple organs and areas of your body, causing widespread symptoms (1, 2, 3).


Symptoms of chemical intolerance may affect and limit someone’s daily life, job or school performance, and social life. In severe cases, chemical intolerance may lead to disability. It may have physical, emotional, social, and economic consequences.


Symptoms of Chemical Intolerance


Chemical intolerance may lead to a variety of symptoms. Symptoms of chemical intolerance may include:

  • Headaches or migraines

  • Rashes or other skin issues

  • Sore throat, congestion, or other respiratory symptoms

  • Chest pain or breathing problems

  • Asthma

  • Fatigue

  • Brain fog and trouble concentrating

  • Confusion and memory issues

  • Muscle and joint pain or stiffness

  • Bloating, gas, diarrhea, or other digestive complaints

  • Changes in heart rhythm

  • Mood changes

Triggers of Chemical Intolerance

Chemical intolerance may be triggered by a variety of chemicals, including but not limited to (3):

  • Tobacco smoke

  • Auto fuel and exhaust

  • Chlorine

  • Perfumes or cologne

  • Aftershave

  • Hair spray

  • Nail polish

  • Body wash or shampoo

  • Other body or beauty products

  • Insecticide

  • Pesticides

  • Paint

  • Plastics

  • New carpet

  • Varnish

  • Tile cleaner

  • Other cleaning products

  • Air fresheners

  • Restroom deodorizers

  • Markers

  • Asphalt pavement

What Are Mast Cells?

Your mast cells are a certain kind of white blood cells in connective tissues, including your digestive tract, skin, respiratory tract, urinary tract, reproductive organs, surrounding your nerves, and near your blood vessels and lymph vessels. Your mast cells are responsible for storing histamine and other inflammatory mast cell mediators that they can release to protect your body when they encounter an allergen.

What Is Mast Cell Activation Syndrome?

Your mast cells play a critical role in your immune system and overall health. Overactive mast cells, however, can increase the risk of mast cell disorders, including mast cell activation syndrome (MCAS). MCAS is a complex health condition that can lead to inflammation, symptoms, and health problems across your entire body (4, 5, 6, 7).

Symptoms of Mast Cell Activation Syndrome


Symptoms of MCAS may vary from person to person. Symptoms can be widespread affecting several areas of your body. They may be mild to severe. Many of the symptoms of

MCAS are similar to chemical intolerance. Your symptoms of MCAS may include:


  • Rashes, eczema, and other skin issues

  • Hives

  • Itching

  • Low blood pressure

  • Heart palpitations

  • Chest pain

  • Headaches of migraines

  • Fatigue

  • Brain fog

  • Weakness

  • Dizziness

  • Loss of appetite or low appetite

  • Rapid weight loss or weight gain

  • Rhinitis

  • Gastrointestinal troubles, including abdominal pain, diarrhea, nausea, and vomiting

  • Nervous system symptoms, such as anxiety

  • Vision changes

Triggers of Mast Cell Activation

Mast cell activation may be triggered by a variety of factors, including:

  • Mold

  • Allergens, including insect bites, gluten, other foods, and preservatives

  • Infections, including viruses and fungi

  • Chemicals and other toxins, including conventional cleaning and personal hygiene products

  • Heavy metals, including mercury from dental work

  • Smells, including perfumes and other conventional beauty or body products

  • Medications, including antibiotics, ibuprofen, and opiate pain relievers

  • Physical or psychological stress from anxiety, exercise, lack of sleep, pain, rapid temperature changes, or other factors

  • Hormonal changes, including hormonal fluctuations during the menstrual cycle

  • Mast cell hyperplasia, a rare health condition related to certain chronic infections or cancers

The Connection Between Mast Cells and Chemical Intolerance

A 1996 paper published in Toxicology has described chemical intolerance as a two-stage disease process called toxicant-induced loss of tolerance (TILT). It explains that chemical intolerance starts with exposure to chemicals, which may be a series of lower-level exposures or an acute, more serious exposure. This exposure may lead to a loss of tolerance and consequently multi-system symptoms of chemical intolerance (8).


Chemical intolerance often develops in people, who formerly had no problems with these chemicals or toxins, after a specific acute exposure or repeated low-level exposure. The origin of these chemical intolerances and related symptoms have been linked to chemical toxicity and allergies, however, the entire mechanism of the process hasn’t been clear. A new study has shed some light on the connection between your mast cells and chemical intolerance.


This 2021 study published in Environmental Sciences Europe has used a 50-question tool called the Quick Environmental Exposure and Sensitivity Inventory (QEESI) to understand the connection between mast cells and chemical intolerance. This instrument is used as an international reference standard to diagnose chemical intolerance. They looked at 147 patients with MCAS, 345 participants who reported chemical intolerances, and 76 healthy control participants.


Researchers found that 59% of the participants with MCAS also met the criteria for chemical intolerance. They found that having MCAS may increase the likelihood of developing or having chemical intolerance. The results also showed that both symptoms and triggers of chemical intolerance and MCAS largely overlap.


It seems that environmental exposure to chemicals can disrupt your mast cells, which can lead to both mast cell activation and chemical intolerance. These results may help doctors to find some answers and offer some solutions for multisystem symptoms and intolerance that can often feel mysterious and complex. It also helps us move one step closer in understanding the role of environmental chemicals and toxin exposure in chronic health issues (9).


Solutions for Mast Cell Activation and Chemical Intolerance


Understanding the connection between mast cells and chemical intolerance is key to recovery. You have to address both mast cell activation and chemical intolerance to reduce your symptoms. To stabilize your mast cells and reduce the risk and symptoms of chemical intolerance, I recommend the following strategies:


Reduce Exposure to Chemicals and Toxins

Avoid chemicals, heavy metals, and environmental toxins. Instead of conventional cleaning, body, and beauty products, opt for organic, natural, or homemade options. Reduce the use of plastics. Use a high-quality air filtration system to improve your indoor air. Buy organic food or grow your own food without pesticides.


Detoxify Your Body

Help your body to detoxify from chemicals, heavy metals, mold, viruses, and other triggers of mast cell activation. Hydrate your body by drinking at least 10 - 12 glasses of water per day. Support detoxification through the skin by increasing sweating through exercise and infrared sauna use. Try glutathione to protect your mitochondria from oxidative stress and activated charcoal to absorb and remove toxins (10, 11). Support your gut with an anti-inflammatory diet and probiotics.


Reduce Your Histamine Bucket

Eat plenty of low-histamine, anti-inflammatory, nutrient-dense whole foods, such as greens, vegetables, herbs, fruits, eggs, pasture-raised poultry, grass-fed beef, and wild-caught fish. Avoid high-histamine foods that can trigger histamine release, or may act as DAO enzyme blockers, and increase histamine levels as described in this article. Avoid medications that may trigger mast cell activation. Reduce your stress and anxiety. Exercise and move your body regularly. Improve your sleep.


Try Mast Call-Stabilizing Foods and Supplements

Try foods that may help to stabilize your mast cells, including watercress, moringa, chamomile, Thai ginger, apples, Brazil nuts, peaches, nettle, onion, fiber-rich foods, and quercetin-rich foods (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23). You may try supplementation with natural antihistamines and mast cell stabilizers, such as quercetin, resveratrol, curcumin, vitamin C, nettle leaf, and luteolin. DAO enzyme may be helpful (24, 25, 26, 27, 28, 29, 30).

Next Steps

1. Working with a healthcare practitioner knowledgeable in MCAS and histamine intolerance is the best way to get to the root cause of your symptoms and to create an individualized treatment plan. I welcome you to start a personalized functional medicine consultation with me. You may book your consultation here.


2. Check out my Histamine Intolerance Course here. Learn on your own time, from anywhere. Get an inside look at the most helpful functional medicine tests for pinpointing imbalances, ways to identify and manage the most common (and sometimes surprising) mast cell triggers, and learn what to eat, what to avoid, and why.