What it is
Mast cell activation syndrome is a condition in which mast cells release their chemical mediators inappropriately, causing recurring symptoms across several body systems. Under the widely used consensus criteria it is diagnosed only when three things are met together: typical recurrent symptoms of mast cell mediator release, an objective rise in blood tryptase during an episode (at least 20% above the person's own baseline plus 2 ng/mL), and improvement on medicines that block or stabilise mast cells.
Signs and symptoms
Urticaria
Hives (urticaria) are a common skin sign during episodes of mast cell mediator release.
Angioedema
Deeper swelling of the skin (angioedema), often around the face or lips, can occur during episodes.
Flushing
Sudden flushing, a warm reddening of the skin, is a characteristic feature of mast cell mediator release.
Pruritus
Itching (pruritus) is a frequent skin symptom during episodes.
Gastrointestinal symptoms
The gut is commonly involved, with symptoms such as cramping, nausea, and diarrhoea during episodes.
Recurrent anaphylaxis
Some people have recurrent anaphylaxis, severe whole-body allergic-type reactions, often without an identifiable allergy.
Transient rise in serum tryptase
A temporary rise in blood tryptase during a symptom flare, at least 20% above the person's baseline plus 2 ng/mL, is the objective marker used to confirm that mast cells are activating.
Treatment and management
What the research describes, not a recommendation. Treatment decisions belong with your clinician.
This covers treatments that appear in the published research mapped here. Investigational and experimental therapies are not included, so their absence is a boundary of this map, not a sign they do not exist.
H1/H2 antihistamines
H1 and H2 antihistamines, which block the effects of histamine released by mast cells, are a first-line treatment and often reduce symptoms substantially; a response to mast-cell-targeting medicines is itself part of the diagnostic criteria.
Used to help with: Mast cell activation syndrome.
“The administration of H1 and/or H2 antihistamines drugs +/- a leukotriene receptor antagonist resulted in a marked reduction in symptoms.”
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How to read the evidence labels
Where this comes from
This guide is built from 1 published source(s). Every claim above links back to one of them. Click any source ID to read the original on PubMed.