Mast cell activation syndrome is a condition that causes mast cells to release an inappropriate amount of chemicals into your body. This causes allergy symptoms and a wide range of other symptoms.
What Is Mast Cell Activation Syndrome?
Mast cell activation syndrome, also called MCAS or mast cell activation disorder, is a condition that causes mast cells to release high amounts of chemicals into your body. This chemical release causes you to have many symptoms.
Mast cells are blood cells that are part of your immune system. They help you fight infections but are also involved in allergic reactions. Mast cells live longer than normal cells, growing in your bone marrow, gastrointestinal tract, skin, and airways.
When you come into contact with an allergen or substance that causes allergies, mast cells release chemicals called mediators that cause your body’s reaction to the substance. Some chemicals are released right away, and some take longer.
In a healthy person, these chemicals help protect and heal. In someone with mast cell activation syndrome, they cause distressing symptoms.
Sometimes mast cells can be activated or triggered by things like:
- Infections
- Medications
- Insect venom
- Reptile venom
- Fragrances
- Stress
- Exercise
- Food
People who have mast cell activation syndrome might have a lot of allergy symptoms and lots of episodes of anaphylaxis without a clear cause.
Mast Cell Activation Syndrome vs. Mastocytosis
Sometimes mast cell activation syndrome is confused with mastocytosis. These are both types of mast cell disease, but they are different conditions.
Mastocytosis. Mastocytosis is a rare disease in which extra mast cells gather in organs in your body like the spleen, liver, gut, and skin. This is usually caused by genetic changes causing mast cells to make more of themselves.
This causes you to have too many cells and have a random chemical release that can overwhelm your body and make you sick. These cells might grow fast, be very sensitive, and constantly and randomly release chemicals.
This rare disease can cause skin growths and a blood disorder called leukemia.
Mast cell activation syndrome. This condition doesn’t cause extra cells to gather in your organs. Instead, it happens when mast cells release too many chemicals and cause these allergy symptoms.
What Causes Mast Cell Activation Syndrome?
Mast cell activation syndromes can be primary, secondary, and idiopathic, depending on why they happen.
Primary disorders of mast cell activation
Primary disorders of mast cell activation usually happen when there’s a problem with the mast cell or its parent cells, which causes extra production of mast cells. This problem may occur when there is a mutation in a gene called KIT.
These primary disorders of mast cell activation include mastocytosis, monoclonal mast cell activation syndrome (MMAS), mast cell sarcoma, mast cell leukemia, and mastocytoma.
Secondary disorders of mast cell activation
Secondary disorders of mast cell activation happen when the body encounters a trigger that causes it to produce too many mast cells. This trigger could:
- Involve IgE antibodies like food, drugs, or venom
- Be unrelated to IgE antibodies like drugs, physical activity, stress, or infections
Idiopathic mast cell activation syndrome
No one knows the exact cause of this type of mast cell activation syndrome. It's called an idiopathic condition because it's not caused by any other disease or related to a clear allergy or cause.
People who have this syndrome might have a hard time pinpointing the exact thing that triggers allergic reactions. New triggers might come up a lot.
MCAS Symptoms
Many different symptoms affect lots of your body systems all at once. These can happen after eating foods, smelling certain fragrances, exercising, and more.
Some key symptoms include:
- Swelling
- Itching
- Rashes
- Inflammation
- Vomiting
- Chronic pain
- Flushing
- Diarrhea
- Constipation
- Sweats
- Abdominal pain
- Fatigue
Mast cell activation syndrome neurological symptoms
MCAS may also cause symptoms that involve your brain and nerves, including:
- Memory problems
- Headaches
- Balance problems
- Fainting
- Brain fog
- Fast heart rate or slow heart rate
- Shortness of breath
- Anxiety
- Depression
- Mood swings
- Heart palpitations
- Sleeping problems
- Trouble swallowing
- Irregular heart rhythm
- Sensitivity to sound or light
- Dizziness or lightheadedness
- Excessive drooling
Symptoms of anaphylactic shock
You’re likely to have a potentially life-threatening allergic reaction called anaphylactic shock when you have MCAS. Symptoms of anaphylactic shock include:
- Fast heartbeat
- Low blood pressure
- Fainting
- Hives
- Itchy, pale, or flushed skin
- Difficulty breathing
- Difficulty swallowing
- Swelling in your throat, lips, and tongue
- Stomach pain
- Tightness in your chest
- Diarrhea
- Vomiting
- Wheezing
- Lightheadedness
- Confusion
- Sudden weakness
- Unconsciousness
Call 911 immediately if you or anyone around you shows these symptoms.
Signs your allergies could be caused by MCAS
Some signs that your allergies could be caused by MCAS include:
- Symptoms in more than one system
- Symptoms that come and go or are cyclical
- Lots of different triggers
- Difficulty figuring out what the triggers are
- A dramatic change in symptoms
MCAS Diagnosis
Your symptom history, a physical exam, and lab tests will help your doctor make a diagnosis. Your doctor will look for these specific things:
- Allergy symptoms and other symptoms in two or more organ systems that keep coming back or are chronic
- Higher than normal levels of tryptase, histamine, or prostaglandins in your blood
- Getting better after using antihistamine medications or other drugs that block chemicals released by mast cells
If you meet all three of these criteria, your doctor might diagnose you with mast cell activation syndrome.
Relationship between mast cell activation syndrome and POTS
Postural orthostatic tachycardia syndrome (POTS) is a condition where too little blood gets to the heart when a person stands up after lying down. It causes:
- Lightheadedness or fainting
- A quick rise in heart rate, causing it to have 30 more beats per minute or a heart rate of over 120 beats per minute
These symptoms happen within 10 minutes of standing up. You will feel better again when you lie down.
People with POTS have reported having MCAS symptoms, which has led scientists to consider that the two conditions may be related. They believe that MCAS may be connected to POTS as:
- A trigger
- A coexisting condition
However, more research is needed to understand the relationship between the two conditions. Knowing that you may have POTS symptoms with MCAS can help your doctor treat you better.
MCAS Treatment
There is no cure for the condition. You will need to avoid triggers and take the medications your doctor prescribes to manage your symptoms.
Antihistamine medications and other drugs that block these chemicals can help. These can include:
- First-generation H1 blockers: diphenhydramine and hydroxyzine
- Second-generation H1 blockers: cetirizine, fexofenadine, and loratidine
- H2 blockers: famotidine and ranitidine
- Aspirin
- Leukotriene inhibitors: montelukast and zafirlukast
- Corticosteroids
- Monoclonal antibodies: omalizumab
If you have anaphylactic reactions, your doctor might also give you an auto-injector epinephrine pen for emergencies.
Sometimes, people also react to the ingredients in the medications, meaning it can take some time to find the proper treatment.
Stress can cause mast cells to be activated. MCAS symptoms can cause more stress and worry, leading to a vicious cycle of symptoms. You can manage your stress levels by:
- Talking to a therapist
- Connecting with your friends
- Resting
- Using mindfulness techniques
- Doing gentle exercise
- Practicing your hobby
What should you know about MCAS and vagus nerve stimulation?
Vagus nerve stimulation (VNS) involves electrically stimulating the vagus nerve -- the nerves responsible for rest and digestion -- with a pulse generator device. VNS is approved for treating epilepsy and depression that medicines can’t treat.
Some research suggests that VNS may help regulate the process that activates mast cells and causes them to release substances that cause your body’s symptoms. But research is needed to see if it can help treat MCAS.
Living With Mast Cell Activation Syndrome
Living with MCAS can be stressful, and the more symptoms you have, the more likely you are to have distressing emotions like anxiety. These emotions can affect your everyday life and overall quality of life. But you can learn to cope with these challenges, improve your physical and mental health, and live a more active life with MCAS.
Here are some tips that may help:
Have a support system: Don’t hesitate to speak with your loved ones whenever you want to talk to someone about your symptoms. They may help you in any way they can by going on errands for you or following you to your doctor’s appointments. Their support can go a long way in helping you feel empowered while living with MCAS.
Join a support group: It can feel isolating living with a serious condition like MCAS. A support group with people who have the same condition and symptoms creates a safe and comfortable space to talk about living and coping with MCAS. You can find online and in-person support groups on websites like The Mast Cell Disease Society and Mast Cell Action.
Limit exposure to triggers: Work with your doctor to identify and understand your specific triggers and create a plan to avoid them in the best way possible for you. Potential triggers can include medications, certain foods, alcohol, and stress.
Manage stress levels: Stress can trigger MCAS episodes or make symptoms feel worse. You can manage your stress levels by prioritizing rest in your daily life. You can add relaxation exercises like deep breathing, taking a gentle walk, meditating, journaling, and listening to music in your everyday routine.
Speak with a mental health professional: Living with MCAS can feel overwhelming, and you might need to see a therapist or other mental health professional on how to navigate life and manage any potential mental health problems tied to MCAS, like anxiety and depression.
Have self-injectable epinephrine at all times: Having MCAS puts you at a high risk of anaphylaxis, a life-threatening reaction. It helps to have your EpiPen on hand in case you show anaphylaxis symptoms like difficulty breathing, lip swelling, and chest tightness.
Mast cell activation syndrome diet
Food can trigger MCAS, so working with a dietitian to improve your diet is helpful. Ask your doctor for a referral to a dietitian. Your dietitian may introduce you to a low-histamine diet if they confirm you can’t tolerate high-histamine foods.
A low-histamine diet involves avoiding foods that are high in histamine or that may trigger histamine release. High-histamine foods include:
- Avocado
- Tomatoes
- Spinach
- Canned or smoked fish
- Eggs
- Nuts
- Chocolates
- Cheese
- Processed meat
- Pork
- Citrus fruits
- Bananas
They can also teach you how to cook in a way that won't cause histamine to build up. You may have to choose baking, boiling, and air frying over other cooking methods.
Takeaways
Mast cell activation syndrome (MCAS) causes a host of symptoms that can seriously affect your physical and mental health. It may happen for no obvious reason or be triggered by different things that you may interact with in everyday life, like sunlight, medications, food, stress, and alcohol. Having MCAS also puts you at risk of anaphylactic shock. Get immediate medical help if you have symptoms like hives, itchy skin, swelling in your throat, lips, and tongue, and tightness in your chest. Follow your treatment plan and speak with a doctor about lifestyle and dietary changes to make.
Mast Cell Activation Syndrome FAQs
Does MCAS ever go away?
No, MCAS never goes away. However, treatment can help manage how often and how serious your symptoms appear.
Which foods trigger mast cells?
People with MCAS often have a reaction to foods including monosodium glutamate (MSG), artificial food dyes and flavorings, chocolate, food preservatives, alcohol, shellfish, pineapples, and tomatoes.
What are the most common mast cell triggers?
Potential mast cell triggers include:
- Heat, cold, or sudden temperature changes
- Tiredness
- Stress
- Exercise
- Food
- Alcohol
- Medication
- Venoms
- Infections
- Sunlight
