Mast Cell Activation Syndrome (MCAS)

Home / Mast Cell Activation Syndrome (MCAS)

Mast cell activation syndrome (MCAS) occurs when the mast cells(a type of WBC) in our body release excess mast cells, resulting in severe allergic reactions. Mast cells are allergy cells responsible for immediate allergic reactions. They cause allergic symptoms by releasing mediators stored inside them or made by them. In allergic reactions, release occurs as […] Read More

Top Doctors For Mast Cell Activation Syndrome (MCAS) Treatments

Mast Cell Activation Syndrome (MCAS)

Mast cell activation syndrome (MCAS) occurs when the mast cells(a type of WBC) in our body release excess mast cells, resulting in severe allergic reactions. Mast cells are allergy cells responsible for immediate allergic reactions. They cause allergic symptoms by releasing mediators stored inside them or made by them. In allergic reactions, release occurs as the allergy antibody IgE (a mediator), which is present on the mast cell surfaces, binds to the allergens (proteins that cause allergies). Mast cells are part of your immune system. They are found in your bone marrow and the surrounding of your blood vessels.

Risk Factors of Mast Cell Activation Syndrome (MCAS)

Certain conditions always trigger incidences of MCAS, but it may not be easy to figure out what triggered it.  Such common triggers include:
  • Allergic type, e.g., dyes (food coloring, pigments in makeup, radiographic dyes), etc.
  • Insect bites, venoms of snakes, jellyfish, insects, and spiders.
  • Certain foods, alcohol
  • Certain types of grass.
  • Drug-induced, such as antibiotics (e.g., ibuprofen and opiate pain relievers).
  • Anxiety.
  • Pain.
  • Exercise.
  • Extreme tiredness.
  • Rapid temperature changes.
  • Infections.
  • Hormonal changes, such as that which occurs during a menstrual cycle.
  • Perfumes.
  • Choking chemical odors.
  • Mast Cell Hyperplasia
MCH is a rare condition occurring with some cancers and chronic infections. Any MCAS in which the trigger cannot be traced is called idiopathic MCAS.

Complications of MCAS

MCAS illness is a syndrome with symptoms that rapidly spread into various body systems. If not managed on time, then mast cell activation syndrome can lead to anaphylactic shock, a life-threatening condition that can lead to death. The most common complications are:
  • Anaphylactic reactions
  • Blood disorders: which include anemia and poor blood clot
  • Peptic ulcer disease
  • Reduced bone density
  • Organ failure [1]

Mast Cell Activation Syndrome (MCAS) Diagnosis

Diagnosing MCAS is hard because of its overlapping symptoms with many other conditions. In diagnosing MCAS, you must meet the following criteria:
  •  Symptoms must be recurrent, affect at least two body systems, and there’s no other condition causing them.
  • Blood or urine tests performed during an episode show higher markers for mediators than when you aren’t having an episode.
  • Bone marrow biopsy, skin biopsy.
  • Genetic testing
  • Imaging tests include x-rays, CT scans, USG, bone scans [2].
  • Medications that block the effects of the mast cell mediators or their release resolve the symptoms.
Before the diagnosis of your condition, your doctor will:
  • Review your medical history.
  • Give you a physical exam.
  • Suggest blood and urine tests to rule out any other causes of your symptoms.
  • Have you avoided certain foods and medications for some time to narrow what might be your triggers.
  • Ask you to keep a detailed log of your episodes, covering any new food you ate, medications you had before it started, etc.

MCAS Treatment

MCAS can only be managed but cannot be cured. Treating the symptoms can also help to discover the cause of MCAS. The treatments include: 1. Mast Cell Stabilizers. These prevent the release of mediators from mast cells. 2. NSAID: Aspirin used. 3. H1 or H2 Antihistamines. They block the effects of histamines, one of the major mediators that release mast cells, such as:
  • Diphenhydramine.
  • Hydroxyzine.
  • Loratadine.
  • Ranitidine.
  • Famotidine.
4. Antileukotrienes. These block the effects of leukotrienes [another common mediator]. They include:
  • Montelukast.
  • Zafirlukast.
  • Zileuton.
5. Corticosteroids These are used for the treatment of edema, wheezing, and hives. NOTICE: They should be used as the last card. Epinephrine injection is necessary for more severe symptoms, such as anaphylactic shock. In addition, Omalizumab, a monoclonal antibody [which blocks the binding of IgE to its receptors], has been reported to reduce mast cell reactivity and sensibility to activation, reducing anaphylactic episodes. 6. Helpful Diets i. Adopt a low histamine diet. ii. Avoid eating:
  • Junks.
  • Cured meats. 
  • Canned fish.
  • Alcohol.
  • Prickled and fermented foods. 
  • Berries.
  • Nuts.
  • Citrus fruits.
  • Dairy yeast.
  • Chocolate.
  • Soy sauce.
  • Tomatoes.
  • Vinegar.
  • Preservatives.
Cut down foods that damage the gut or cause inflammation. Take probiotics and a DAO enzyme (Generic name: Umbrellux DA)], such as:
  • Yogurt.
  • Kefir.
  • Tempeh.
  • Sauerkraut.
  • Kimchi.
  • Miso.
  • Prickles.
Take helpful nutrients. Some of these include:
  • Vitamin B6.
  • Alpha-lipoic acid.
  • Vitamin C.
  • Selenium.
  • Omega-3.
  • N-acetylcysteine.
  • Methylfolate.
  • SAMe.
  • Riboflavin.
Foods that include such nutrients include:
  • Salmon.
  • Walnut.
  • Tuna.
  • Spinach.
  • Banana.
  • Soya beans.
  • Oats.
  • Broccoli.
  • Cabbage.
  • Eggs.
  • Turkey.
Add supportive herbs to your diet. Take the following veggies to support your MCAS treatment:
  • Nigella sativa.
  • Butterbur.
  • Turmeric.
  • Ginger.
  • Peppermint. 
symptoms of Mast Cell Activation Syndrome (MCAS)
Picture Courtesy: annallergy


Too many mediators can cause symptoms in nearly all systems of your body. The most commonly affected areas are your nervous system, heart, gastrointestinal tract, and skin. 

Signs of MCAS range from mild to life-threatening. Indications pointed out in different parts of your body might include:


  • Itching.
  • Watering.


  • Itching.
  • Running.
  • Sneezing.

Mouth and throat:

  • Itching.
  • Swelling in the tongue or lips.
  • Swelling in the throat (thereby blocking air from entering your lungs).


  • Itching.
  • Hives.
  • Flushing.
  • Sweating.

Heart and blood vessels:

  • Low blood pressure.
  • Rapid heartbeat.


  • Breathing difficulty.
  • Wheezing.

Stomach and intestines:

  • Diarrhea.
  • Nausea.
  • Cramping.
  • Abdominal pains.

Nervous system:

  • Dizziness.
  • Headache.
  • Extreme tiredness.

In extreme cases, one suffering from mast cell activation syndrome may experience anaphylactic shock (a life-threatening condition that causes a rapid drop in your blood pressure, a weak pulse, and narrowing of the airways in your lungs that restricts breathing).


The real cause of MCAS is not known. However, a study carried out in 2013 suggests a genetic linkage to MCAS. More research is still needed in this area.


Can mast cell activation be reversed?

Most patients accurately diagnosed with MCAS can get strikingly better, even if they have been suffering for several years.

What foods reduce histamine?

Eating foods low in histamine can reduce histamine levels. Such foods include:

  • Fresh meat and freshly-caught fish.
  • Non-citrus fruits.
  • Eggs.
  • Gluten-free grains, such as rice and quinoa.
  • Cooking oils, such as olive oil.
  • Fresh vegetables, except tomatoes, avocadoes, spinach, and eggplant.
  • Dairy substitutes, such as coconut milk and almond milk.

How do you test for mast cell activation syndrome?

Testing for MCAS is complex due to the overlapping symptoms with other conditions. The diagnosis requires a patient elevation of mediators such as serum tryptase, 24-hour N-methylhistamine, or 11βPGF2 during at least two episodes with a negative workup for systemic mastocytosis or one episode in the patients whose serum tryptase is consistently greater than 15ng/ml.

What foods cause mast cell activation?

The allergy to certain foods differs from one individual to another. The cause of MCAS remains unknown, although a study in 2013 linked it to hereditary factors. Some foods show allergic tendencies, nevertheless. 

Some foods have more tendency to react overall. These include:

  • Monosodium glutamate [MSG].
  • Alcohol.
  • Shellfish.
  • Artificial food dyes.
  • Flavorings.
  • Food preservatives.
  • Pineapples.
  • Tomatoes.
  • Tomato-based products.
  • Chocolate.

What contributes to the recurrent allergic reactions in my body?

In allergic reactions, the release comes when the allergy antibody [IgE], present on the mast cell surface to the allergen, sends it out. Episodes of MCAS are always triggered by something challenging to find out. Such triggers include:

  • Allergens.
  • Drugs.
  • Stress.
  • Perfume fragrance.
  • Hormonal changes.
  • Mast cell hyperplasia (a rare condition that recurs in some cancer and chronic conditions).



  1. Mayoclinic 
  2. Mayoclinic