Unnoticed. Unmistakable.

This is what living with a mast cell disease can look like, unnoticed by most, unmistakable to the person living it.

Awareness Day. 20 october.

One Day. Every Story. Unmistakable.

Mast cell diseases can go unnoticed by almost everyone, and still be unmistakable to the person living with it. On 20 October, people living with a mast cell disease, their families and their advocates come together from around the world to change that, sharing real stories so what’s invisible to most becomes impossible to miss. 

This year, we’re asking you to help make it unmistakable too. Learn how.

About mast cell diseases

A mast cell disease can look different for everyone, but these 3 things tend to stay the same.

Often invisible

Symptoms can be easy to miss, or often mistaken for something else.

Years, not days

Because symptoms overlap with so many other conditions, many people are misdiagnosed for years.

Whole-body impact

Can affect the skin, gut, heart and nervous system, often all at once.

Get involved

Help us raise awareness on Mastocytosis & Mast Cell Diseases Awareness Day

Resources available in 10 languages

Patient Videos

Meet the people living it

Sophie

Australia

“Even if I don’t look like I’m in pain, my symptoms are still unmistakable.”

Waltraud

Germany

“I have been living with a mast cell disease since I was four years old.”

Filomena

Portugal

“I have been living with a mast cell disease since I was four years old.”

Filomena

Portugal

“I have been living with a mast cell disease since I was four years old.”

Filomena

Portugal

“I have been living with a mast cell disease since I was four years old.”

Filomena

Portugal

“I have been living with a mast cell disease since I was four years old.”

Patient Stories

Different lives, all living with diseases that hide in plain sight

What is a 
Mast Cell Disease?

Learn more about mast cell diseases, such as mastocytosis, mast cell activation syndrome (MCAS) and symptomatic hereditary alpha tryptasemia (HaT), via the resource links.

Fact sheets

Five patient fact sheets, available in ten languages

Three leading specialists share practical insights into mastocytosis, idiopathic MCA) and symptomatic HaT.

Understanding life with mast cell diseases: view insights from our global community.

With thanks to

Our sponsors

The 2026 Awareness Day campaign wouldn’t be possible without the support of