Systemic Mastocytosis (SM)

Systemic mastocytosis is a rare blood disease that is caused by too many mast cells, a type of white blood cell, being produced in the bone marrow. This disease is rarely inherited. It is usually acquired due to genetic mutations.1 

Because the body produces too many mast cells, they accumulate in abnormal quantities in the connective tissues of various organs, including the skin, liver, spleen, lymph nodes, lungs, bones, and digestive tract. Mast cells are especially prevalent in organs that are directly exposed to the environment, such as the skin, lungs, and digestive system.1,2

Mast cells are activated by environmental triggers, which cause them to release histamine and other chemicals into the blood. Histamine is a protein associated with allergic reactions to certain substances (allergens) that provoke an inflammatory response of the immune system. This immune response causes a runny nose, sneezing, red or watery eyes, nasal congestion, itching, skin flushing, hives, and rashes.1,2

When histamine is released in greater amounts, more severe symptoms can occur, such as abdominal cramping, diarrhea, nausea, vomiting, gastric reflux, shortness of breath, low blood pressure, problems with attention and memory, headache, and, most seriously, anaphylaxis. Organs may have difficulty functioning normally when large amounts of histamine are circulating throughout the body.1

Self-Care Recommendations

While there is currently no cure for systemic mastocytosis, there are certain steps that can be taken to reduce the risk of reactions and manage them effectively when they occur.

Emergency Medications


It is recommended that anyone who is diagnosed with systemic mastocytosis carry 2 EpiPens, which automatically inject epinephrine into the thigh muscle during an acute attack of anaphylaxis. Once injected, EpiPens improve breathing, stimulate the heart, elevate a dropping blood pressure, reverse hives, and reduce swelling of the throat, lips, or face. It is important to carry 2 of them because patients may require 2 doses en route to the hospital. Patients should ensure that they have them every time they leave their home.3,4 

EpiPens should be carried in an insulated, easily identifiable container to help emergency responders or helpers find them, if necessary. EpiPens must be protected from the heat, as this may cause them to malfunction or deliver less epinephrine than is needed.3,5

For patients who also take a beta blocker for heart problems, their doctor may advise that they carry a glucagon pen to take prior to using an EpiPen. This is because beta blockers interact with epinephrine, making them less effective, but glucagon helps to avoid this outcome.3


Depending on an individual’s situation and disease type, extra doses of antihistamines, such as H1 and H2 blockers, may prevent more serious, anaphylactic reactions from occurring if taken in a timely manner. H1 blockers include cetirizine and piriton, and H2 blockers include ranitidine and famotidine.3

It is important that patients establish a routine for taking their medications regularly. Using a pill organizer and setting alarms to take medications at specific times during the day may help those who struggle with forgetfulness. It is important for patients to continue taking medications as prescribed by their doctor, even if they are feeling better.3

Doctors may prescribe new medications to try for systemic mastocytosis. It is important to start taking these medications slowly with a responsible person and an EpiPen nearby in case a patient reacts to these medications.3

It is recommended that patients with systemic mastocytosis avoid taking medications that trigger mast cell activation and release of histamine, including6,7

  • Blood-thinners/nonsteroidal anti-inflammatory drugs (NSAIDS) such as aspirin and dextran
  • Opioids such as morphine and codeine
  • Antibiotics including those in the fluoroquinolone family and polymyxin B
  • Muscle relaxants such as decamethonium, gallamine, and D-tubocurarine
  • Procaine, an anesthetic medication
  • Scopolamine, a motion sickness medication
  • Other substances such as vitamin B1 supplements, alcohol, and contrast dyes for imaging

If contrast dye is unavoidable for certain imaging studies, the administration of medications such as corticosteroids and histamine blockers prior to these imaging procedures is recommended.6

Medical Alert Bracelets

Another step that is highly advisable is purchasing a medical alert bracelet to wear at all times. A list of a patient’s medical conditions can be inscribed on the bracelet. This may help others understand the patient’s condition and advise them on needed actions if the patient is unable to speak to them for any reason.3


Some foods are naturally high in histamine, while others trigger a release of histamine by activating mast cells. Both may increase the likelihood of an allergic reaction. Spicy foods, alcohol, fermented beverages and foods, hot beverages, aged foods like cheese, legumes, citrus fruits, shellfish, processed or preserved foods, packaged meats, and spoiled foods (such as leftovers) may trigger symptoms, so it is best to avoid them. Fresh foods are best.8,9 

The way patients cook their food and the temperature at which they are stored may also influence the histamine within them. Boiling meat decreases histamine compared to grilling. Cheeses stored at lower temperatures have less histamine.8,10

Two diets—the elimination diet and the low-histamine diet—may help identify food triggers and reduce overall symptoms.3

Some clinics suggest taking quercetin and vitamin C supplements to stabilize mast cells by inhibiting histamine release.11

Read more about systemic mastocytosis diet and nutrition


One potential trigger for allergic reactions in systemic mastocytosis is exercise because it elevates the body’s internal temperature and is considered a form of stress on the body. Extreme temperature changes and stress trigger mast cell activation, so avoiding strenuous exercise, especially on hot, humid days, is advised.3,12 

Light exercise like weightlifting, walking, yoga, or pilates in a place where it is possible to stay cool, such as a gym with air conditioning, is an alternative. Taking a spray bottle or battery-operated fan may help patients keep cool. Wearing layers is important to maintain an ideal body temperature; they are easy to take off if a patient find themselves getting too hot, but they also prevent extreme cold exposure.3

People with systemic mastocytosis are at increased risk of developing bone mineral density disorders like osteoporosis/osteopenia, which can lead to fractures. It is important to engage in some form of weight-bearing exercise like walking, jumping, or jogging to keep the bones strong and healthy. Patients should try different forms of exercise to find out which ones work best for them.3

Be aware that gyms may use strong cleaning products and pool chemicals, have temperature control issues (too cold or hot), and expose patients to other people’s perfumes. If this is the case and it is hard for a patient to exercise in a gym setting, they should try exercising at home or outside when the weather is not too cold, hot, or humid.3

Clothing and Skin Care

Loose-fitting, comfortable clothing should be worn to avoid friction, scratching, rubbing, or constriction of the skin, which may trigger a response. Wearing clothes made of natural fibers and keeping the skin moisturized may also reduce itching.3

Layers should be worn that are easy to remove when a patient starts to feel uncomfortable.3 


Bees, insects, and animals that sting or bite should be avoided, as these are frequent triggers for allergic reactions. Wearing insect repellent that does not trigger an allergic reaction or using insect netting or a screened-in porch might help to prevent insect bites. Allergic reactions to insect stings and bites range from mild local reactions at the site of the sting or bite to severe allergic reactions that are life threatening. It can trigger histamine release that increases blood flow and white blood cell count around the affected area causing inflammation and swelling.12,13

Topical steroids and antihistamine creams may reduce the localized reaction if a patient does get bitten or stung.13


Stress management is important to decrease emotional stress and anxiety, which may trigger the immune system.3,11,12 

Deep breathing exercises, routine meditation, and yoga are ways to help manage stress. Moderating activities and taking things at a patient’s own pace can also reduce stress.3

Cleaning and Perfumes

Air fresheners, essential oil diffusers, bathroom sprays, and perfumes should be avoided. Patients should try using natural cleaners like vinegar and sodium bicarbonate (baking soda) or other methods of cleaning without using strong chemicals that might trigger a reaction.3


  1. Systemic mastocytosis. MedlinePlus. Updated August 18, 2020. Accessed April 21, 2022.
  2. Mastocytosis. Cleveland Clinic. Accessed April 21, 2022.
  3. Self-care for mast cell diseases. The UK Mastocytosis Support Group. Accessed April 21, 2022. 
  4. Jaishankar D. Systemic mastocytosis follow-up. Medscape. Updated June 21, 2021. Accessed April 21, 2022.
  5. Nath I. If your auto-injector gets hot, it may fail. Allergic Living. March 11, 2020. Accessed April 21, 2022. 
  6. Habashy J. Mastocytosis treatment & management: medical care. Medscape. Updated September 16, 2020. Accessed April 21, 2022.
  7. Mast cell degranulation – an overview. ScienceDirect. Accessed April 21, 2022.
  8. Foods high in histamine. WebMD. Accessed April 21, 2022. 
  9. Habashy J. Mastocytosis treatment & management: diet. Medscape. Updated September 16, 2020. Accessed April 21, 2022. 
  10. Chung BY, Park SY, Byun YS, et al. Effect of different cooking methods on histamine levels in selected foods. Ann Dermatol. 2017;29(6):706-714. doi:10.5021/ad.2017.29.6.706
  11. Hoffman B. 12 tips for living with mast cell activation syndrome. Hoffman Centre. November 28, 2017. Accessed April 21, 2022.
  12. Habashy J. Mastocytosis treatment & management: activity. Medscape. Updated September 16, 2020. Accessed April 21, 2022. 
  13. Hemmer W, Wantke F. Insect hypersensitivity beyond bee and wasp venom allergy. Allergol Select. 2020;4:97-104. doi:10.5414/ALX02123E

Reviewed by Debjyoti Talukdar, MD, on 4/27/2022.