Management of Mast Cell Activation Syndrome

Treatment Approach

The American Academy of Allergy, Asthma, and Immunology recommends the use of non-sedating H1 antihistamines, such as fexofenadine or cetirizine, in doses 2 to 4 times higher than those approved by the FDA, combined with H2 antihistamines for gastrointestinal symptoms, as first-line treatment for mast cell activation syndrome 1
The use of non-sedating H1 antihistamines can reduce dermatological manifestations, tachycardia, and abdominal discomfort, and is more effective as prophylaxis than as acute treatment 1
The American College of Allergy, Asthma, and Immunology suggests that H2 antihistamines can be added as first-line therapy specifically for gastrointestinal symptoms, and may also help attenuate cardiovascular symptoms 1
Cromoglicato de sódio oral is particularly effective for gastrointestinal symptoms, including abdominal distension, diarrhea, and colic, and may also have benefits for neuropsychiatric manifestations 1

The National Comprehensive Cancer Network recommends pre-anesthetic treatment, including the use of anxiolytics, antihistamines, and possibly corticosteroids, to reduce the frequency and/or severity of mast cell activation events 2
Propofol, sevoflurano, and isoflurano are considered safer agents for induction and maintenance of anesthesia, while fentanil and remifentanil are preferred analgesics 2
Lidocaína and bupivacaína are considered safer local anesthetics, while atracúrio and mivacúrio should be avoided due to the risk of mast cell activation 2

The American Academy of Allergy, Asthma, and Immunology recommends the use of epinephrine auto-injectors in patients with a history of anaphylaxis or angioedema, and instructs patients on how and when to use them 1
Patients with recurrent hypotensive episodes should be trained to assume a supine position as quickly as possible, and to use a wedge pillow for diarrhea and a basin for emesis after rolling onto their side or abdomen 1
Albuterol can be inhaled using a nebulizer or metered-dose inhaler to treat symptoms or signs of bronchospasm 1

The American Academy of Allergy, Asthma, and Immunology recommends H1-receptor antihistamines as cornerstone treatments for MCAS, targeting dermatologic manifestations, tachycardia, and abdominal discomfort 3, 4
H2-receptor antihistamines are commonly used to treat abdominal symptoms in MCAS patients 3, 5
Cyproheptadine is specifically recommended for diarrhea and nausea in MCAS patients 5, 6
Oral cromolyn sodium is particularly effective for gastrointestinal symptoms in MCAS patients 3, 6
Leukotriene receptor antagonists or 5-lipoxygenase inhibitor can be added, particularly for dermatologic symptoms in MCAS patients 3, 4

The American Academy of Allergy, Asthma, and Immunology suggests that medications should be introduced cautiously as some patients may experience paradoxical reactions 3, 6
Aspirin may help reduce flushing and hypotensive episodes associated with PGD2 secretion in MCAS patients, but should be introduced in a controlled clinical setting 3
For refractory cases, omalizumab may be considered when MCAS is resistant to standard mediator-targeted therapies 3
Systemic corticosteroids might help some MCAS patients, but should be tapered quickly to limit adverse effects 3

Patients with MCAS should be prescribed epinephrine autoinjectors if they have a history of systemic anaphylaxis 4, 6

First-generation H1 antihistamines can cause significant sedation and cognitive decline, particularly in elderly MCAS patients 5, 4
Medication trials for MCAS should be conducted in a controlled setting with emergency equipment available 4
Careful trigger identification and avoidance is crucial alongside pharmacologic interventions for MCAS patients 4