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Mast Cell Activation Syndrome (MCAS)

Mast Cell Activation Syndrome (MCAS)

Mast cells are integral to our immune system and play an important function in mediating both innate and humoral immunity. When functioning properly, mast cells work to create healthy levels of inflammation and signaling to the immune system so that any foreign invaders can be silenced. However, the problem comes when the cells become over-activated, releasing histamine, the chemical that is responsible for allergic symptoms, such as puffy eyes, rash, skin flushing, itchiness, etc.

Symptoms of Mast Cell Activation

  • Life-threatening allergic reactions, aka Anaphylaxis
  • Flushing of the face, neck, and chest
  • Itching, +/- rash
  • Hives, skin rashes
  • Angioedema (swelling)
  • Nasal itching and congestion
  • Wheezing and shortness of breath
  • Throat itching and swelling
  • Headache and/or brain fog, cognitive dysfunction, anxiety, depression
  • Diarrhea, nausea, vomiting, abdominal pain, bloating, gastroesophageal reflux disease (GERD)
  • Bone/muscle pain, osteosclerosis, osteopenia, osteoporosis
  • Light-headedness, syncope/fainting
  • Rapid heart rate, chest pain
  • Low blood pressure, high blood pressure at the start of a reaction, blood pressure instability

Triggers of Mast Cell Activation

  • Heat, cold, or sudden temperature changes
  • Stress: emotional, physical, including pain, or environmental (i.e., weather changes, pollution, pollen, pet dander, etc.)
  • Exercise
  • Exhaustion/Fatigue
  • Various Food or beverages, including alcohol
  • Medications (Antibiotics, etc.)
  • Various odors
  • Venoms (bee, wasp, biting insects, such as flies, mosquitos, and fleas, etc.)
  • Chronic Infections (viral, bacterial or fungal)
  • Mechanical irritation, friction, vibration
  • Sun/sunlight


Diagnosing mast cell activation can be challenging. Increases in serum mast cell tryptase and in urine levels of N-methylhistamine, certain prostaglandins such as 11B -Prostaglandin F2α (11B-PGF2α), and/or various Leukotrienes such as Leukotriene E4 (LTE4). Given the fact that these intermediaries are only present in the blood for minutes after an insult, getting a proper diagnosis can be challenging. 


Treatment begins with identifying what might be triggering the mast cells or causing them to be overactivated. The challenge with this however is that in many cases there is no known insult for the antigen to pinpoint. In other words, the mast cell activation seemed to come out of nowhere. This is called idiopathic mast cell activation and can be very frustrating for both patients and providers. 

In our experience, much of the problems with mast cells lie in the gut, and therefore healing things like leaky gut syndrome, treating small intestinal bacterial overgrowth, treating dysbiosis, addressing any underlying malabsorption issues is imperative.   Food allergies must be addressed. Any chronic infection such as mold or Lyme illness needs to be treated otherwise the immune system will be continually confused, creating an overactive immune response. Autoimmunity is generally a cofactor and is the result of immune dysregulation. Therefore, any autoimmune conditions also need to be treated. Sometimes addressing food allergies as well as going on low tyramine or low histamine diet is helpful. As always, mental and emotional stress, that present needs to be treated. We often find that an overactive limbic system is a major factor in chronic MCAS, and until this is addressed, not much progress can be made. 

  • Treat the gut (leaky gut, food allergies, intolerances, etc.)
  • Treat any underlying infections
  • Adress autoimmunity
  • Low histamine/low tyramine diet
  • Address emotional issues, stress
  • Adress overactive limbic system 

Herbal options

Luckily, there are many herbal options to help stabilize mast cells. Vitamin C can be extraordinarily helpful as well as quercetin, stinging nettle, ginger, bromelain, curcumin, and others. Palmitoylethanolamide (PEA), a substance found in soybeans, egg yolks, alfalfa, and peanuts reduces mast cell migration and degranulation and reduces the pathological over-activation of these cells. Since these are alike to consume throughout the day supplement companies have created various combinations of these. Unfortunately, some of our patients are unable to tolerate even oral supplements, and therefore we have to look at other options such as homeopathy and neural field therapy.

Pharmaceutical options

Many of those who suffer from chronic mast activation need pharmaceutical support. Various over-the-counter H1 and H2 blockers can be effective such as Zyrtec, Claritin, Allegra, Famotidine, and Xyzal. Singular or montelukast, a leukotriene inhibitor, is sometimes beneficial. If the source of the mast cell activation is food allergy and origin, cromolyn sodium can be invaluable. In severe cases, Xolair shots may be indicated, but insurance coverage can be a challenge. 


Mast cell activation syndrome unfortunately has become all too common and can be a struggle for those who are battling chronic illness. Stabilizing the mast cells early in the process is a critical component to recovery from chronic illness. If you think you are struggling with mast cell activation, please contact our office for further evaluation and treatment.