Halsey Diagnosed with Mast Cell Activation Syndrome and a Host of Other Ailments. What is MCAS?

Ashley Nicolette Frangipane — better known as “Halsey” — has disclosed that they have been diagnosed with multiple ailments since the birth of their baby last July.

The singer posted a series of Instagram stories and TikToks earlier this week explaining:

A lot of you guys have been wondering what’s going on with my health and some of you saw a TikTok yesterday basically confirming that I’m allergic to literally everything.

Obviously my health has changed a lot since I got pregnant and giving birth. I started getting really, really, really sick.

Since the birth of son Ender, Halsey says they have been hospitalized with anaphylaxis numerous times resulting in diagnoses for Ehlers-Danlos syndrome, Sjögren’s syndrome, mast cell activation syndrome and postural orthostatic tachycardia syndrome.

Let’s define these one-by-one:

Ehlers-Danlos syndrome is a group of inherited disorders that affect the connective tissues — primarily skin, joints and blood vessel walls.

Sjögren’s syndrome is a disorder of the immune system identified by its two most common symptoms — dry eyes and a dry mouth. It often accompanies other autoimmune diseases such as lupus and rheumatoid arthritis.

Postural orthostatic tachycardia syndrome (POTS) is a condition that affects blood flow and causes the development of symptoms — usually lightheadedness, fainting and an uncomfortable, rapid increase in heartbeat — that come on when standing up from a reclining position and relieved by sitting or lying back down.

To understand MCAS, we must first understand what mast cells do.

The Role of Mast Cells

Mast cells play an important role in how the immune system responds to certain bacteria and parasites and help control other types of immune responses. They release chemicals known as mediators such as histamine, heparin, cytokines, and growth factors in response to certain stimuli known as secondary activation because they are triggered by external stimuli. In people with allergies, mast cells respond to IgE antibodies triggered by harmless substances, thus causing symptoms.

Mast Cell Activation Syndrome

According to the American Academy of Allergy, Asthma & Immunology, sometimes mast cells become defective and release mediators because of abnormal internal signals.

MCAS is a condition in which the patient experiences repeated episodes of the symptoms of anaphylaxis — allergic symptoms such as hives, swelling, low blood pressure, difficulty breathing, and severe diarrhea.

MCAS Treatment

The treatment for acute episodes should follow the recommendations for treatment of anaphylaxis, starting with epinephrine, if indicated by the severity of symptoms.

Antihistamines, such as the first generation histamine type 1 receptor blockers diphenhydramine and hydroxyzine, can be effective for itching, abdominal discomfort and flushing, but their use may be limited by side effects (sleepiness). Second generation antihistamines, including loratadine, cetirizine and fexofenadine, are preferable due to fewer side effects.

Treatment with histamine type 2 receptor blockers, such as ranitidine or famotidine, can be helpful for abdominal pain and nausea.

Aspirin blocks production of prostaglandin D2 and can reduce flushing.

Montelukast and zafirlukast block the effects of leukotriene C4 (LTC4) and zileuton blocks LTC4 production, so these reduce wheezing and abdominal cramping.

Corticosteroids are helpful for edema, hives and wheezing but should only be used as a last resort.

Omalizumab (which blocks binding of IgE to its receptors) has been reported to reduce mast cell reactivity and sensitivity to activation which can reduce anaphylactic episodes.

In summary, those diagnosed with MCAS — like those diagnosed with food allergies and allergies to insect venoms and substances including latex — should be prescribed epinephrine and always take two epinephrine auto-injectors along everywhere, every time in case anaphylaxis strikes.