Mast Cell Activation Syndrome

What is mast cell activation syndrome (MCAS)?

MCAS is also known as mast cell activation disorder. Mast Cell Activation Syndrome is an immune condition. This is a condition in which mast cells act inappropriately and they excessively release chemicals that result in chronic symptoms. These symptoms sometimes cause anaphylaxis and near anaphylaxis attacks. Chronic MCAS is hard to diagnose because symptoms can be mild or atypical. The main symptoms of MCAS affect the cardiovascular system, the dermatological system, the gastrointestinal system, the neurological system and respiratory system.

People with Mast Cell Activation Syndrome have a normal amount of mast cells that are hyper-responsive. This is opposed to people that have mastocytosis because they have abnormally large amount of mast cells. MCAS is currently under investigation and being researched on because not a lot is known about it. MCAS is often found in people with Ehlers-Danlos syndrome, postural orthostatic tachycardia syndrome, common variable immunodeficiency and Lyme disease. [4]

mast cell activation syndrome


There are no known causes for mast cell activation syndrome. This condition appears to be inherited. The excessive chemical release from the mast cells cause the symptoms. MCAS can be a mild condition or it can become exacerbated by stress. Sometimes the condition can also develop slowly and get worse over time. Some factors can be associated with MCAS such as hypothyroidism, autoimmune issues, neoplastic disease, parasitic infections and other infections. [3, 4]


  • Dermatological
    • Flushing skin
    • Easily bruised
    • Reddish or pale complexion
    • Itchy skin

mast cell activation syndrome

  • Cardiovascular
    • Lightheaded
    • Dizziness
    • Pre-syncope (pre fainting)
    • Syncope (fainting)
    • Hypotension or hypertension
    • Palpitations
    • Chest pain

mast cell activation syndrome

  • Gastrointestinal
    • Diarrhea
    • Abdominal cramping
    • Abdominal discomfort
    • Nausea
    • Vomiting
    • Hyperacidity, peptic ulcers and/or dyspepsia
    • Enlarged liver, swelling of the liver and jaundice
    • Enlarged spleen
    • Loss of appetite
  • Neurological and Psychological
    • Brain fog, confusion
    • Irritability
    • Short term memory loss and poor attention span
    • Word recall problems
    • Headaches, migraines
    • Peripheral neuropathy
  • Respiratory
    • Congestion
    • Coughing
    • Wheezing
    • Spasms in the lungs
    • Shortness of breath
  • Eye sight
    • Pain/discomfort
    • Inflammation
    • Blurred vision
  • Musculoskeletal
    • Osteoporosis
    • Osteopenia (in young people too)
    • Fractures
    • Joint pain
  • General
    • Fatigue and malaise
    • Intolerances to food, drugs and chemicals
    • Being cold all the time
    • Vascular instability
    • Anemia and other low blood counts
    • Overactive spleen
    • Disease of the lymph lodes
    • Bleeding disorders
    • Weight loss
    • Urinary problems like urinary urgency and dysuria
    • Anaphylaxis (difficulty breathing, swollen body parts, strange taste in the mouth, sore/itchy eyes, anxiety, MCAS is a autoimmune disease that causes hives, itchy skin, flushing/pale skin, warmth/fever, high or low pulse, nausea, emesis, diarrhea, dizziness, syncope and loss of consciousness)
  • Mast cell activation syndrome triggers, symptoms can be worsened by common triggers (but are very person specific)
    • Food and drinks (especially alcohol and high histamine foods)
    • Extreme temperatures
    • Smells in the air like smoke or perfume
    • Exercise and/or exertion
    • Stress
    • Food triggers
    • Hormone changes like in puberty, pregnancy and menstrual cycles

mast cell activation syndrome


MCAS is difficult to diagnose. A lot of the time symptoms are too mild and do not show flagrant signs of the syndrome. Most of the time people see many different kinds of doctors for diagnosis because of the multi system symptoms that occur. Diagnosis needs a holistic view of the symptomology. A major hurdle to this diagnosis is also that many doctors lack knowledge of the syndrome and its symptoms. [4]

The common formula for diagnosis of MCAS is:

  • Symptoms of recurrent mast cell release
    • Recurrent abdominal pain, skin flushing, diarrhea, skin itching, congestion, coughing, tightness in the chest, wheezing and lightheaded
  • Mast cell mediator lab results
  • Medications to block/treat mast cell mediators improve symptoms [4]

Differential Diagnosis

  • Urticaria
  • Carcinoid syndrome
  • Phaeochromocytoma
  • Renal cancer
  • Medullary thyroid carcinoma
  • Pancreatic cell tumor
  • Inflammatory bowel disease
  • Irritable bowel syndrome
  • Malabsorption syndrome
  • Zollinger-Ellison syndrome
  • Hepatitis
  • Cirrhosis


MCAS is treated by symptoms. Common medication treatments include mast cell mediators, H1 antihistamines, H2 antihistamines, anti-leukotrienes and NSAIDs. The pharmacies need to be aware that the fillers, binders and dyes can be triggers for people with MCAS and thus avoided. Lifestyle changes are needed for people with MCAS so that triggers can be avoided. A mast cell activation disorder diet is low histamine and it can help prevent food triggers. [4]


MCAS has no cure. It is important for people with MCAS to prevent triggers. The life span for people with MCAS is normal but their quality of life can be affected a little or a lot. Sometimes people with MCAS are disabled by it and cannot work. [4]

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What to read next?

Reference List:

1. Genetic Gene, Available from:

2. Patient Info, Available from:

3. TMS for a Cure, Available from:

4. Wikipedia, Available from:

5. Photographing Pots, Available from:

6. YouTube, Available from: AND

7. Tumblr, Available from:

8. Detail for all Diseases, Available from:,d.amc&psig=AFQjCNHGTKAgtc9m_glgRYaIV5QS8nadOw&ust=1479317070849115

3 thoughts on “Mast Cell Activation Syndrome

  • 23/05/2018 at 8:38 PM

    It is very comprehensive and useful description of Mast cell activation syndrome, but short in the treatment models.
    I have read aspirin and high dose of vitamin C improve the symptoms, hope other readers post their opinion.

  • 23/05/2019 at 10:41 PM

    Non-steroidal anti-inflammatory drugs such as aspirin and ibuprofen can actually make symptoms of MCAS even worse. Especially when somebody is suffering angioedematous symptoms, things like aspirin are best avoided simply because they can make the swelling even worse. A drug such as cromoglycate, if one is not allergic to monoglycerides and rather long carbon chain fatty acid type substances and their derivatives, such as I am, work quite well. Dexamethasone, and other such corticosteroids, are far more feasible for people with MCAS disorder.

    A typical first treatment regimen would consist of H1 blockers; and a short course of corticosteroids such as Prednisone or prednisolone at the order of 30 to 60 mg daily for five days; with both of these drugs taken concurrently.

    For long-term therapy, cromoglycate ampoules which can be opened, the contents delivered into a glass of water, can be consumed 4 times a day– once a half hour before meals, and a half hour before bedtime. Unfortunately, in Australia they have never heard of this substance, and so I need to get out of this country very quickly.

  • 15/05/2020 at 7:45 AM

    What’s the differentiation or concurrent relationship with MCAS and urticaria? Can’t urticaria exist as a symptom of MCAS? How can we tell the two apart?


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