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PubMed This is a summary of 18 peer-reviewed journal articles Updated
Allergy and Immunology · Systemic Mastocytosis

Treatments and Targeted Therapies: Taking Control

At a Glance

Systemic mastocytosis treatment involves a two-pronged approach: managing daily symptoms with antihistamines and mast cell stabilizers, and using targeted KIT inhibitors like avapritinib to address the underlying disease. Carrying an EpiPen and an emergency protocol letter is essential for safety.

The treatment of systemic mastocytosis (SM) has undergone a dramatic shift. For many years, doctors could only manage the symptoms of the disease. Today, thanks to advances in genetics, we have precision medicine—treatments that target the specific biological cause of the disease (the KIT mutation) to actively modify the course of the illness [1][2].

Your treatment plan will depend heavily on your symptom severity and your subtype.

Step 1: Managing the “Mediator” Symptoms

For many patients, particularly those with Indolent Systemic Mastocytosis (ISM), a major goal is controlling the release of chemicals (mediators) from mast cells [3].

  • Antihistamines (H1 and H2 Blockers): This is the frontline of defense. H1 blockers (like cetirizine) help with itching and flushing, while H2 blockers (like famotidine) target stomach acid and digestive issues [3][4].
  • Mast Cell Stabilizers: Cromolyn sodium is often used to help “calm” mast cells, particularly those in the gastrointestinal tract, reducing cramping and diarrhea [5][4].
  • Dietary Management: While not a medication, adopting a low-histamine diet can be a highly effective, complementary tool. Reducing your intake of high-histamine foods gives you another actionable way to take control of daily GI distress and flushing [6].
  • Epinephrine (EpiPen): This is a vital safety tool. Because mastocytosis increases the risk of severe reactions (anaphylaxis), carrying an epinephrine auto-injector is an essential part of the care plan [7].
  • Omalizumab: For patients with severe, repeated anaphylaxis that doesn’t respond to standard blockers, this injectable medication is sometimes used “off-label” to help prevent life-threatening reactions [8][9].

Step 2: Targeted KIT Inhibitors

Targeted therapies are designed to “fit” into the mutated KIT D816V receptor and turn the “stuck switch” off. This reduces the actual number of mast cells in the body [10].

  1. Avapritinib (Ayvakit): This highly selective therapy represents a breakthrough in care [11][12]. It was initially approved for Advanced SM to shrink mast cell burden and improve organ function [13][14]. Recently, the FDA also approved Avapritinib for adults with Indolent Systemic Mastocytosis (ISM), offering a powerful, disease-modifying option to patients whose daily symptoms remain uncontrolled by standard antihistamines.
  2. Midostaurin (Rydapt): This multi-kinase inhibitor is approved for advanced forms of SM. It blocks the signals that tell mast cells to grow, providing clinical benefit in aggressive variants [15][16].

Step 3: Cytoreductive and Other Therapies

In cases of Advanced SM where targeted inhibitors aren’t the best fit, or as an additional tool, other treatments may be used:

  • Cladribine (2-CdA): A type of chemotherapy (cytoreductive therapy) that is very effective at killing mast cells. It is often reserved for specific advanced cases or when other treatments have failed [17][18].
  • Steroids (Glucocorticoids): These may be used temporarily for severe flares or digestive malabsorption to reduce inflammation quickly [4].

Be Prepared: Medical Alert Protocols

Because many ER staff and local doctors lack experience with mastocytosis, you should always carry a Medical Alert card or bracelet. Additionally, work with your specialist to draft an Emergency ER Protocol Letter. This letter should outline your diagnosis, critical triggers (like contrast dye or anesthetics), and exact instructions for treating anaphylaxis in your specific case.

The “best” treatment is the one that aligns with your specific disease burden and quality-of-life goals. To ensure your treatments are tracked appropriately over time, see Building Your Care Team and Long-Term Monitoring.

Common questions in this guide

How are the daily symptoms of systemic mastocytosis treated?
Daily mediator symptoms like itching, flushing, and digestive issues are typically managed first with antihistamines. If symptoms persist, mast cell stabilizers like cromolyn sodium or a low-histamine diet may be added to help calm the mast cells.
What are targeted KIT inhibitors for mastocytosis?
Targeted KIT inhibitors, such as avapritinib and midostaurin, are medications designed to block the mutated KIT gene responsible for mast cell overgrowth. Unlike symptom-management drugs, these therapies can actually reduce the number of abnormal mast cells in your body.
Will I need an EpiPen if I have systemic mastocytosis?
Yes, patients with systemic mastocytosis are at a higher risk for severe allergic reactions, including anaphylaxis. Carrying an epinephrine auto-injector is an essential safety precaution for managing sudden, life-threatening flares.
What is the role of a low-histamine diet in managing mastocytosis?
Adopting a low-histamine diet is a complementary strategy to help reduce the overall chemical burden in your body. Avoiding high-histamine foods can be highly effective in controlling daily gastrointestinal distress and flushing.
How do I prepare for emergencies with mastocytosis?
You should always carry a medical alert card and have an emergency protocol letter from your specialist. This letter should detail your diagnosis, specific triggers to avoid like certain anesthetics, and exact instructions for treating anaphylaxis in the ER.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Are my symptoms controlled well enough with antihistamines, or should we consider adding a mast cell stabilizer like cromolyn sodium?
  2. 2.Given my specific subtype, am I a candidate for targeted KIT inhibitors like avapritinib or midostaurin?
  3. 3.If I continue to have severe reactions despite standard treatment, would omalizumab be an appropriate off-label option for me?
  4. 4.What are the specific side effects I should watch for with targeted therapy, and how will we monitor for them?
  5. 5.Is an epinephrine auto-injector (EpiPen) necessary for my case, and how should I use it during a flare?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (18)
  1. 1

    Patient-Reported Outcomes and Provider Perceptions of Systemic Mastocytosis: Results From the PRISM Study.

    Triggiani M, Hobart J, Alvarez-Twose I, et al.

    Clinical and experimental allergy : journal of the British Society for Allergy and Clinical Immunology 2025; (55(9)):784-794 doi:10.1111/cea.70101.

    PMID: 40579689
  2. 2

    NCCN Guidelines® Insights: Systemic Mastocytosis, Version 3.2024.

    Gotlib J, Gerds AT, Abdelmessieh P, et al.

    Journal of the National Comprehensive Cancer Network : JNCCN 2024; (22(2 D)).

    PMID: 38862005
  3. 3

    Management of Mastocytosis and Mast Cell Activation in Children.

    Carter MC, Lange M, Alvarez-Twose I, et al.

    The journal of allergy and clinical immunology. In practice 2026; (14(1)):30-42 doi:10.1016/j.jaip.2025.11.016.

    PMID: 41285204
  4. 4

    Childhood Cutaneous Mastocytosis: Revisited.

    Swarnkar B, Sarkar R

    Indian journal of dermatology 2023; (68(1)):121 doi:10.4103/ijd.ijd_264_22.

    PMID: 37151240
  5. 5

    Updates on Kinase Inhibitors in Allergy.

    Dispenza MC, Kim BS

    The journal of allergy and clinical immunology. In practice 2026; (14(2)):336-343 doi:10.1016/j.jaip.2025.10.047.

    PMID: 41285205
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    Drugs and Vaccines Hypersensitivity in Children with Mastocytosis.

    Mori F, Crisafulli G, Bianchi A, et al.

    Journal of clinical medicine 2022; (11(11)) doi:10.3390/jcm11113153.

    PMID: 35683540
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    Clinical impact of the TPSAB1 genotype in mast cell diseases: A REMA study in a cohort of 959 individuals.

    González-de-Olano D, Navarro-Navarro P, Muñoz-González JI, et al.

    Allergy 2024; (79(3)):711-723 doi:10.1111/all.15911.

    PMID: 37818990
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    Successful treatment with Omalizumab of a child affected by Systemic Mastocytosis: clinical and biological implications.

    Bossi G, Brazzelli V, De Amici M, et al.

    Italian journal of pediatrics 2023; (49(1)):6 doi:10.1186/s13052-022-01402-7.

    PMID: 36639823
  9. 9

    Efficacy of Omalizumab in Indolent Systemic Mastocytosis.

    Slapnicar C, Trinkaus M, Hicks L, Vadas P

    Case reports in hematology 2019; (2019()):3787586 doi:10.1155/2019/3787586.

    PMID: 31637065
  10. 10

    Systemic Mastocytosis, Version 2.2019, NCCN Clinical Practice Guidelines in Oncology.

    Gotlib J, Gerds AT, Bose P, et al.

    Journal of the National Comprehensive Cancer Network : JNCCN 2018; (16(12)):1500-1537 doi:10.6004/jnccn.2018.0088.

    PMID: 30545997
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    Novel approaches to treating advanced systemic mastocytosis.

    Gilreath JA, Tchertanov L, Deininger MW

    Clinical pharmacology : advances and applications 2019; (11()):77-92 doi:10.2147/CPAA.S206615.

    PMID: 31372066
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    Target Therapies for Systemic Mastocytosis: An Update.

    Sciumè M, De Magistris C, Galli N, et al.

    Pharmaceuticals (Basel, Switzerland) 2022; (15(6)) doi:10.3390/ph15060738.

    PMID: 35745657
  13. 13

    Indirect treatment comparisons of avapritinib versus midostaurin for patients with advanced systemic mastocytosis.

    Pilkington H, Smith S, Roskell N, Iannazzo S

    Future oncology (London, England) 2022; (18(13)):1583-1594 doi:10.2217/fon-2021-1509.

    PMID: 35114819
  14. 14

    Avapritinib versus midostaurin or cladribine in advanced systemic mastocytosis: A retrospective real-world external control study.

    Reiter A, Gotlib J, Álvarez-Twose I, et al.

    Leukemia research 2025; (157()):107919 doi:10.1016/j.leukres.2025.107919.

    PMID: 40712393
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    Midostaurin: A Multiple Tyrosine Kinases Inhibitor in Acute Myeloid Leukemia and Systemic Mastocytosis.

    Schlenk RF, Kayser S

    Recent results in cancer research. Fortschritte der Krebsforschung. Progres dans les recherches sur le cancer 2018; (212()):199-214 doi:10.1007/978-3-319-91439-8_10.

    PMID: 30069632
  16. 16

    Midostaurin treatment in FLT3-mutated acute myeloid leukemia and systemic mastocytosis.

    Kayser S, Levis MJ, Schlenk RF

    Expert review of clinical pharmacology 2017; (10(11)):1177-1189 doi:10.1080/17512433.2017.1387051.

    PMID: 28960095
  17. 17

    Treatment of Indolent and Advanced Systemic Mastocytosis.

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    PMID: 35615325
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    Response and resistance to cladribine in patients with advanced systemic mastocytosis: a registry-based analysis.

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    Annals of hematology 2023; (102(8)):2077-2085 doi:10.1007/s00277-023-05180-y.

    PMID: 37012462

This page provides educational information about systemic mastocytosis treatments. Always consult your hematologist or immunologist before starting or changing any medications or diets.

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