Table of ContentsView AllTable of ContentsSymptoms of Mast Cell Activation SyndromeWhat Causes MCAS?DiagnosisMast Cell Activation Syndrome TreatmentCoping
Table of ContentsView All
View All
Table of Contents
Symptoms of Mast Cell Activation Syndrome
What Causes MCAS?
Diagnosis
Mast Cell Activation Syndrome Treatment
Coping
Mast cell activation syndrome (MCAS) is a disorder in whichmast cells, a normal type of cell found in your immune system, release excessive amounts ofhistaminesand other chemicals that lead to allergy-like symptoms in your body.
People living with MCAS may experience common allergic symptoms like itching and sneezing. They also may have thyroid changes, heart rate and blood pressure fluctuations, fatigue, and nausea.The underlying cause isn’t always clear and MCAS can be difficult to diagnose.
This article explains what is known about MCAS and its symptoms and causes. It presents how healthcare providers continue working toward a consensus on MCAS diagnosis and treatment.
Verywell / Nusha Ashjaee
The symptoms of mast cell activation syndrome can affect various systems of the body. These systems can include:
The symptoms associated with MCAS can range from only a few to a sweeping set of unpleasant issues, but they typically involve two or more organ systems of the body.The symptoms include:
MCAS symptoms may flare up on a cyclical basis, vary in severity, and change over time.
People with this condition may have other overlapping illnesses as well, such as:
However, their presence does not necessarily indicate a MCAS disorder.Additional research is needed to understand the connection these illnesses may have with mast cells.
What Is Indolent Systemic Mastocytosis?
At the present time, MCAS is thought to be a family of disorders with several potential causes. These are classified as primary, secondary, oridiopathic(no clearly identified cause).
In primary MCAS, the cause is an abnormality in the mast cells themselves. One such disorder ismastocytosis, which causes an abnormal amount of mast cells to accumulate in different parts of the body. The two types of mastocytosis are:
MCAS and GeneticsResearch suggests there may be a genetic predisposition to the illness. For example, studies have identified a condition calledhereditary alpha tryptasemia(HAT) that some researchers now consider to be a genetic biomarker (diagnostic indicator) in certain people with MCAS.It’s also more common in people with systemic mastocytosis than in healthy populations.
MCAS and Genetics
Research suggests there may be a genetic predisposition to the illness. For example, studies have identified a condition calledhereditary alpha tryptasemia(HAT) that some researchers now consider to be a genetic biomarker (diagnostic indicator) in certain people with MCAS.It’s also more common in people with systemic mastocytosis than in healthy populations.
Monoclonal MCAS is another primary disorder, in which an abnormal clone of mast cells causes the symptoms.
In idiopathic MCAS, abnormal mast cell activation occurs without any identifiable, consistent trigger, and no primary mast cell disorder can be identified.
What Is Mastocytosis?
Diagnosis of MCAS can be difficult. Currently, there isn’t a test that decisively indicates whether or not someone has MCAS. However, key diagnostic criteria have been identified although new views continue to emerge.
A healthcare provider who is familiar with MCAS may be able to diagnose an individual based on the clinical presentation when two or more organ systems of the body are impacted.
For example, a person with MCAS may have an increased heart rate, a rash, and experience vomiting—all of which occur together and may either resolve spontaneously or with treatment.
During flare-ups of MCAS, a person may have elevated urine or blood levels of chemical mediators like tryptase or histamine during two or more episodes. Lab tests can help support the diagnosis, with tryptase levels in the blood generally considered the most reliable.
Other factors that help a healthcare provider to reach a diagnosis of MCAS are:
Using Differential Diagnosis to Confirm Your Illness
To date, there is no cure for MCAS. The primary goals of treatment are to stabilize mast cells so that they cease to release their chemical mediators, provide relief of symptoms, and minimize known triggers.
Everyone reacts to treatment differently, so it may take a bit of trial and error to find what works for you:
Other mast cell stabilizers such ascromolynmay work to help lessen symptoms as well.
In severe cases of MCAS, corticosteroids may be recommended to mitigate the ongoing cascade of chemical mediators and inflammation.You may need to carry anEpiPenin case of anaphylaxis.
Note that there may be other kinds of medications not mentioned here that your healthcare provider may prescribe you for your symptoms of MCAS.
Regardless of what medications you take, being mindful of your triggers and doing your best to avoid them is best practice.
MCAS can cause a considerable amount of distress for the people who have it, and the illness can be lonely and isolating. Sometimes, no matter how hard you try to avoid potential triggers, the condition flares up anyway.
Online groups and forums are available for sharing treatment strategies, resources, and support. Joining a group can help you to learn what has helped others and what may be helpful to you, too.
Summary
MCAS can lead to a wide range of symptoms, including body-wide reactions, that can be difficult to diagnose. The development of specific diagnostic criteria continues to progress.
MCAS treatment is focused on stabilizing the mast cell behavior through medication, including the use of H1 (histamine) blockers and corticosteroids.
A Word From Verywell
Though there is no known cure for MCAS and the condition can be very frustrating to cope with, rest assured that you can connect with other people who are going through similar experiences. If you’ve been diagnosed with MCAS or suspect you have it, The Mast Cell Disease Society offers a healthcare provider database.It can help you locate a specialist.
8 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Afrin LB, Ackerley MB, Bluestein LS, Brewer JH, Brook JB, Buchanan AD,et al.Diagnosis of mast cell activation syndrome: a global “consensus-2”.Diagnosis (Berl). 2020 Apr 22;8(2):137-152. doi:10.1515/dx-2020-0005Valent P, Akin C, Bonadonna P, Hartmann K, Brockow K, Niedoszytko M,et al.Proposed Diagnostic Algorithm for Patients with Suspected Mast Cell Activation Syndrome.J Allergy Clin Immunol Pract. 2019 Apr;7(4):1125-1133.e1. doi:10.1016/j.jaip.2019.01.006.Weiler CR, Austen KF, Akin C, et al.AAAAI Mast Cell Disorders Committee Work Group Report: Mast cell activation syndrome (MCAS) diagnosis and management.J Allergy Clin Immunol. 2019;144(4):883-896. doi:10.1016/j.jaci.2019.08.023Valent P, Akin C, Nedoszytko B, Bonadonna P, Hartmann K, Niedoszytko M,et al.Diagnosis, Classification and Management of Mast Cell Activation Syndromes (MCAS) in the Era of Personalized Medicine.Int J Mol Sci. 2020 Nov 27;21(23):9030. doi:10.3390/ijms21239030.Nurmatov UB, Rhatigan E, Simons FER, Sheikh A.H1-antihistamines for primary mast cell activation syndromes: a systematic review.Allergy. 2015;70(9):1052-1061. doi:10.1111/all.12672Molderings GJ, Haenisch B, Brettner S, et al.Pharmacological treatment options for mast cell activation disease.Naunyn Schmiedebergs Arch Pharmacol. 2016;389(7):671-694. doi:10.1007/s00210-016-1247-1Kumaraswami S, Farkas G.Management of a Parturient with Mast Cell Activation Syndrome: An Anesthesiologist’s Experience.Case Rep Anesthesiol. 2018;2018:8920921. doi:10.1155/2018/8920921Mast Cell Disease Society.Finding a Physician.Additional ReadingAkin C.Mast cell activation syndromes.J Allergy Clin Immunol. 2017;140(2):349-355. doi:10.1016/j.jaci.2017.06.007American Academy of Allergy Asthma & Immunology.Mast Cell Activation Syndrome (MCAS).Frieri M, Patel R, Celestin J.Mast cell activation syndrome: a review.Curr Allergy Asthma Rep. 2013;13(1):27-32. doi:10.1007/s11882-012-0322-zMolderings GJ, Haenisch B, Bogdanow M, Fimmers R, Nöthen MM.Familial Occurrence of Systemic Mast Cell Activation Disease.PLos ONE. 2013; 8(9): e76241. doi:10.1371/journal.pone.0076241The Mastocytosis Society.Finding a physician.
8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Afrin LB, Ackerley MB, Bluestein LS, Brewer JH, Brook JB, Buchanan AD,et al.Diagnosis of mast cell activation syndrome: a global “consensus-2”.Diagnosis (Berl). 2020 Apr 22;8(2):137-152. doi:10.1515/dx-2020-0005Valent P, Akin C, Bonadonna P, Hartmann K, Brockow K, Niedoszytko M,et al.Proposed Diagnostic Algorithm for Patients with Suspected Mast Cell Activation Syndrome.J Allergy Clin Immunol Pract. 2019 Apr;7(4):1125-1133.e1. doi:10.1016/j.jaip.2019.01.006.Weiler CR, Austen KF, Akin C, et al.AAAAI Mast Cell Disorders Committee Work Group Report: Mast cell activation syndrome (MCAS) diagnosis and management.J Allergy Clin Immunol. 2019;144(4):883-896. doi:10.1016/j.jaci.2019.08.023Valent P, Akin C, Nedoszytko B, Bonadonna P, Hartmann K, Niedoszytko M,et al.Diagnosis, Classification and Management of Mast Cell Activation Syndromes (MCAS) in the Era of Personalized Medicine.Int J Mol Sci. 2020 Nov 27;21(23):9030. doi:10.3390/ijms21239030.Nurmatov UB, Rhatigan E, Simons FER, Sheikh A.H1-antihistamines for primary mast cell activation syndromes: a systematic review.Allergy. 2015;70(9):1052-1061. doi:10.1111/all.12672Molderings GJ, Haenisch B, Brettner S, et al.Pharmacological treatment options for mast cell activation disease.Naunyn Schmiedebergs Arch Pharmacol. 2016;389(7):671-694. doi:10.1007/s00210-016-1247-1Kumaraswami S, Farkas G.Management of a Parturient with Mast Cell Activation Syndrome: An Anesthesiologist’s Experience.Case Rep Anesthesiol. 2018;2018:8920921. doi:10.1155/2018/8920921Mast Cell Disease Society.Finding a Physician.Additional ReadingAkin C.Mast cell activation syndromes.J Allergy Clin Immunol. 2017;140(2):349-355. doi:10.1016/j.jaci.2017.06.007American Academy of Allergy Asthma & Immunology.Mast Cell Activation Syndrome (MCAS).Frieri M, Patel R, Celestin J.Mast cell activation syndrome: a review.Curr Allergy Asthma Rep. 2013;13(1):27-32. doi:10.1007/s11882-012-0322-zMolderings GJ, Haenisch B, Bogdanow M, Fimmers R, Nöthen MM.Familial Occurrence of Systemic Mast Cell Activation Disease.PLos ONE. 2013; 8(9): e76241. doi:10.1371/journal.pone.0076241The Mastocytosis Society.Finding a physician.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Afrin LB, Ackerley MB, Bluestein LS, Brewer JH, Brook JB, Buchanan AD,et al.Diagnosis of mast cell activation syndrome: a global “consensus-2”.Diagnosis (Berl). 2020 Apr 22;8(2):137-152. doi:10.1515/dx-2020-0005Valent P, Akin C, Bonadonna P, Hartmann K, Brockow K, Niedoszytko M,et al.Proposed Diagnostic Algorithm for Patients with Suspected Mast Cell Activation Syndrome.J Allergy Clin Immunol Pract. 2019 Apr;7(4):1125-1133.e1. doi:10.1016/j.jaip.2019.01.006.Weiler CR, Austen KF, Akin C, et al.AAAAI Mast Cell Disorders Committee Work Group Report: Mast cell activation syndrome (MCAS) diagnosis and management.J Allergy Clin Immunol. 2019;144(4):883-896. doi:10.1016/j.jaci.2019.08.023Valent P, Akin C, Nedoszytko B, Bonadonna P, Hartmann K, Niedoszytko M,et al.Diagnosis, Classification and Management of Mast Cell Activation Syndromes (MCAS) in the Era of Personalized Medicine.Int J Mol Sci. 2020 Nov 27;21(23):9030. doi:10.3390/ijms21239030.Nurmatov UB, Rhatigan E, Simons FER, Sheikh A.H1-antihistamines for primary mast cell activation syndromes: a systematic review.Allergy. 2015;70(9):1052-1061. doi:10.1111/all.12672Molderings GJ, Haenisch B, Brettner S, et al.Pharmacological treatment options for mast cell activation disease.Naunyn Schmiedebergs Arch Pharmacol. 2016;389(7):671-694. doi:10.1007/s00210-016-1247-1Kumaraswami S, Farkas G.Management of a Parturient with Mast Cell Activation Syndrome: An Anesthesiologist’s Experience.Case Rep Anesthesiol. 2018;2018:8920921. doi:10.1155/2018/8920921Mast Cell Disease Society.Finding a Physician.
Afrin LB, Ackerley MB, Bluestein LS, Brewer JH, Brook JB, Buchanan AD,et al.Diagnosis of mast cell activation syndrome: a global “consensus-2”.Diagnosis (Berl). 2020 Apr 22;8(2):137-152. doi:10.1515/dx-2020-0005
Valent P, Akin C, Bonadonna P, Hartmann K, Brockow K, Niedoszytko M,et al.Proposed Diagnostic Algorithm for Patients with Suspected Mast Cell Activation Syndrome.J Allergy Clin Immunol Pract. 2019 Apr;7(4):1125-1133.e1. doi:10.1016/j.jaip.2019.01.006.
Weiler CR, Austen KF, Akin C, et al.AAAAI Mast Cell Disorders Committee Work Group Report: Mast cell activation syndrome (MCAS) diagnosis and management.J Allergy Clin Immunol. 2019;144(4):883-896. doi:10.1016/j.jaci.2019.08.023
Valent P, Akin C, Nedoszytko B, Bonadonna P, Hartmann K, Niedoszytko M,et al.Diagnosis, Classification and Management of Mast Cell Activation Syndromes (MCAS) in the Era of Personalized Medicine.Int J Mol Sci. 2020 Nov 27;21(23):9030. doi:10.3390/ijms21239030.
Nurmatov UB, Rhatigan E, Simons FER, Sheikh A.H1-antihistamines for primary mast cell activation syndromes: a systematic review.Allergy. 2015;70(9):1052-1061. doi:10.1111/all.12672
Molderings GJ, Haenisch B, Brettner S, et al.Pharmacological treatment options for mast cell activation disease.Naunyn Schmiedebergs Arch Pharmacol. 2016;389(7):671-694. doi:10.1007/s00210-016-1247-1
Kumaraswami S, Farkas G.Management of a Parturient with Mast Cell Activation Syndrome: An Anesthesiologist’s Experience.Case Rep Anesthesiol. 2018;2018:8920921. doi:10.1155/2018/8920921
Mast Cell Disease Society.Finding a Physician.
Akin C.Mast cell activation syndromes.J Allergy Clin Immunol. 2017;140(2):349-355. doi:10.1016/j.jaci.2017.06.007American Academy of Allergy Asthma & Immunology.Mast Cell Activation Syndrome (MCAS).Frieri M, Patel R, Celestin J.Mast cell activation syndrome: a review.Curr Allergy Asthma Rep. 2013;13(1):27-32. doi:10.1007/s11882-012-0322-zMolderings GJ, Haenisch B, Bogdanow M, Fimmers R, Nöthen MM.Familial Occurrence of Systemic Mast Cell Activation Disease.PLos ONE. 2013; 8(9): e76241. doi:10.1371/journal.pone.0076241The Mastocytosis Society.Finding a physician.
Akin C.Mast cell activation syndromes.J Allergy Clin Immunol. 2017;140(2):349-355. doi:10.1016/j.jaci.2017.06.007
American Academy of Allergy Asthma & Immunology.Mast Cell Activation Syndrome (MCAS).
Frieri M, Patel R, Celestin J.Mast cell activation syndrome: a review.Curr Allergy Asthma Rep. 2013;13(1):27-32. doi:10.1007/s11882-012-0322-z
Molderings GJ, Haenisch B, Bogdanow M, Fimmers R, Nöthen MM.Familial Occurrence of Systemic Mast Cell Activation Disease.PLos ONE. 2013; 8(9): e76241. doi:10.1371/journal.pone.0076241
The Mastocytosis Society.Finding a physician.
Meet Our Medical Expert Board
Share Feedback
Was this page helpful?Thanks for your feedback!What is your feedback?OtherHelpfulReport an ErrorSubmit
Was this page helpful?
Thanks for your feedback!
What is your feedback?OtherHelpfulReport an ErrorSubmit
What is your feedback?
