What is severe asthma?

Let’s start with a key source: eosinophils

Eosinophil graphic
Eosinophil graphic

To understand possible causes of severe asthma attacks, it’s important to understand the role eosinophils (ee-uh-sin-uh-fils) can play.


Eosinophils are normal white blood cells in your body. If you have severe asthma, you may have increased levels of eosinophils, which can worsen inflammation in your lungs. Inflammation can cause severe asthma attacks.


Simple blood testing can measure eosinophil levels to help determine if you have eosinophilic asthma.


Once you have a severe eosinophilic asthma diagnosis, you and your doctor can decide if adding NUCALA may help.

Curious how NUCALA works?

Let’s take a deeper look.

Could you have severe asthma?


If you’re taking all your asthma medications

Asthma controller medicines, including high-dose inhaled corticosteroids.

but still struggling, it could be severe asthma. These are some of the key signs doctors look for when diagnosing severe asthma.

Poor symptom control

Are you coughing, wheezing, having difficulty breathing, frequently using a rescue inhaler, or waking up at night?

Worsening asthma

Having flare-ups? These are also called exacerbations or severe asthma attacks—when symptoms don’t improve and you need to add oral steroids.

ER visits or hospitalizations

Is the severity of your asthma attacks sending you to the ER or requiring hospitalization?

If this sounds familiar, it’s time to talk to your doctor about your current asthma treatments.

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The word on NUCALA

Hear it straight from real people taking NUCALA.

Let’s prep for next steps with your doctor

Did you know most severe asthma can be controlled? To get the right diagnosis, it’s important to be open and honest with your doctor. Use these points to help get the conversation started:

Start by telling your doctor about your asthma management plan.

Tell your doctor when your symptoms get worse. Your symptoms may require you to see a specialist.

Is your asthma interfering with your daily activities? Tell your doctor about your symptoms and how they affect your life.

Ask for blood testing to see if you have severe eosinophilic asthma.

Need help finding a specialist?

Let’s get started.

Doctor discussion guide

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