Mast Cell Activation Syndrome (MCAS)
What is Mast Cell Activation Syndrome (MCAS)?
MCAS is an allergy/immunological condition which can develop in children or adults as part of a spectrum of mast cell disorders (e.g., Mastocytosis, hereditary alpha tryptasemia syndrome or HATS).
What are Mast Cells?
Mast cells are sentinel white blood cells which respond to foreign pathogens. Stated another way, mast cells are like the 'police officers' of the immune system, spotting signs of trouble and calling for backup. Chemicals called mast cell mediators are released too frequently or abundantly in response to triggers. Mast cells can release up to 1200 different types of chemicals or mediators, of which histamine is just one. This can lead to a wide range of symptoms that affect many parts and systems in the body.
What are Mast Cell Triggers?
Certain foods are higher histamine by nature (e.g., citrus, strawberries, pineapple, bananas, avocado) and then certain foods are low histamine (e.g., apples, pears, blueberries). The longer foods are cooked as in a slow cooker or the further away they are from cooking, (e.g., canned, preserved, smoked or dried foods), the more histamine builds in it. Leftovers are higher histamine. Read more about histamine classification here.
When does this become Anaphylaxis?
Anaphylaxis is an acute, life-threatening system reaction that results from the sudden, rapid, systemic release of mediators. If you are in anaphylaxis, you need to call 911 or get to your nearest ER.
MCAS is diagnosed by an allergist/immunologist who specializes in Mast Cell disorders. Please join an MCAS group on Facebook near you to identify MCAS-knowledgable allergists. Typically allergists will want to test your blood and urine for mast cell mediators (e.g., tryptase, histamine, IL-6, etc.) although this can be complicated as there are over 1200 potential mediators and negative tests may not mean you do not have MCAS. Another sign of MCAS is dermatographia.
It is important to note that many MCAS patients do not test positive for any environmental or food allergies skin-prick testing.
How is MCAS related to EDS, POTS and Long COVID?
We know that degranulating mast cells are often related to the onset or worsening of symptoms of both EDS and POTS. It has also been observed that some cases of Long COVID may be due to MCAS.
How is MCAS treated?
If you suspect you have MCAS, you can begin taking H1 anti-histamines such as Zyrtec, Claritin, Allergra, Xyzal. Benadryl is an old generation H1 but is not recommended for long-term use. It is also recommended to simultaneously take an H2 anti-histamine such as Pepcid or Famotidine, as the combination is thought to be stabilizing to mast cells. You should also familiarize yourself with the histamine content of foods and limit your consumption of high histamine foods. There are several dietitians who have written about cooking low histamine. Here is Dr. Leonard Weinstock, a GI doctor, Guide to treatment of MCAS.
Some over-the-counter supplements such as Quercetin, Stinging Nettle, Vitamin C or Luteolin might help to stabilize mast cells: Where can you learn more about MCAS?
MCAS is an allergy/immunological condition which can develop in children or adults as part of a spectrum of mast cell disorders (e.g., Mastocytosis, hereditary alpha tryptasemia syndrome or HATS).
What are Mast Cells?
Mast cells are sentinel white blood cells which respond to foreign pathogens. Stated another way, mast cells are like the 'police officers' of the immune system, spotting signs of trouble and calling for backup. Chemicals called mast cell mediators are released too frequently or abundantly in response to triggers. Mast cells can release up to 1200 different types of chemicals or mediators, of which histamine is just one. This can lead to a wide range of symptoms that affect many parts and systems in the body.
What are Mast Cell Triggers?
- Foods or Alcohol
- Mold exposure
- Chemical or VOC exposure
- Sun/Sunlight
- Poisonous plant exposure
- Heat or cold temperature
- Stress
- Pain
- Surgery
- Wounds
- Exercise
- Fatigue
- Natural odors, perfumes or scents
- Venoms (insects, spiders, fire ants, snakes, mosquitos, etc.)
- Mechanical irritation, friction, vibration
- Drugs (opioids, NSAIDs, antibiotics, local anesthetics) and contrast dyes
- flushing
- headache
- tachycardia
- chest pain
- abdominal pain
- bloating
- reflux
- diarrhea
- vomiting
- cramps
- rashes
- muscle pain
- osteopenia
- itching
- rash
- blood pressure instability
- brain fog
- cognitive dysfunction
- anxiety
- depression
- dizziness
- syncope
- anaphylaxis
Certain foods are higher histamine by nature (e.g., citrus, strawberries, pineapple, bananas, avocado) and then certain foods are low histamine (e.g., apples, pears, blueberries). The longer foods are cooked as in a slow cooker or the further away they are from cooking, (e.g., canned, preserved, smoked or dried foods), the more histamine builds in it. Leftovers are higher histamine. Read more about histamine classification here.
When does this become Anaphylaxis?
Anaphylaxis is an acute, life-threatening system reaction that results from the sudden, rapid, systemic release of mediators. If you are in anaphylaxis, you need to call 911 or get to your nearest ER.
- Mouth: itching, swelling of lips or tongue
- Throat: itching, tightness or closure, hoarseness
- Skin: itching, hives, redness, swelling
- Gut: vomiting, diarrhea, cramps
- Lung: Shortness of breath, cough, wheeze
- Heart: weak pulse, dizziness, passing out
MCAS is diagnosed by an allergist/immunologist who specializes in Mast Cell disorders. Please join an MCAS group on Facebook near you to identify MCAS-knowledgable allergists. Typically allergists will want to test your blood and urine for mast cell mediators (e.g., tryptase, histamine, IL-6, etc.) although this can be complicated as there are over 1200 potential mediators and negative tests may not mean you do not have MCAS. Another sign of MCAS is dermatographia.
It is important to note that many MCAS patients do not test positive for any environmental or food allergies skin-prick testing.
How is MCAS related to EDS, POTS and Long COVID?
We know that degranulating mast cells are often related to the onset or worsening of symptoms of both EDS and POTS. It has also been observed that some cases of Long COVID may be due to MCAS.
How is MCAS treated?
If you suspect you have MCAS, you can begin taking H1 anti-histamines such as Zyrtec, Claritin, Allergra, Xyzal. Benadryl is an old generation H1 but is not recommended for long-term use. It is also recommended to simultaneously take an H2 anti-histamine such as Pepcid or Famotidine, as the combination is thought to be stabilizing to mast cells. You should also familiarize yourself with the histamine content of foods and limit your consumption of high histamine foods. There are several dietitians who have written about cooking low histamine. Here is Dr. Leonard Weinstock, a GI doctor, Guide to treatment of MCAS.
Some over-the-counter supplements such as Quercetin, Stinging Nettle, Vitamin C or Luteolin might help to stabilize mast cells: Where can you learn more about MCAS?
- The Mast Cell Matters Podcast
- Never Bet Against Occam by Dr. Lawrence Afrin
- The Mast Cell Disease Society
- Mast Cell Action
- American Academy of Allergy, Asthma & Immunology
