Up to half of adults living with asthma may have the form of the disease known as eosinophilic asthma. Read more to learn how to tell if you have eosinophilic asthma, how it progresses, and what treatment methods are available.

Nearly 25 million people in the United States are living with asthma. Asthma is a chronic lung disease caused by inflammation in the airways that makes it hard to breathe.

The symptoms and presentation of asthma vary widely — some people may have very mild symptoms, whereas others have symptoms that are more difficult to control.

Many people with severe asthma have a form known as eosinophilic asthma. Eosinophilic asthma is a type of asthma defined by a high presence of eosinophils (a type of white blood cell) within the airways and lungs.

Eosinophils are normally involved in fighting off infections. Too many of them can lead to overactivation of the immune system and increased inflammation. This can cause swelling in the lungs and airways, which makes it difficult to breathe.

In this article, we take a look at some of your most frequently asked questions about eosinophilic asthma, including what makes it different and how to treat it.

Asthma is not just a single disease but a collection of different types that vary based on their causes and responses to different treatment options. Eosinophilic asthma is just one type of asthma.

Compared with other types of asthma, research suggests that eosinophilic asthma is more common in adults; most people develop eosinophilic asthma between 25 and 35 years of age. It’s typically harder to treat than other forms of asthma and may not respond to certain medications, such as corticosteroids, which are commonly used to treat asthma.

As a result, people with eosinophilic asthma may be more likely to develop severe disease than those with non-eosinophilic asthma. A 2021 study found that people with eosinophilic asthma also tend to have worse lung function than those with other forms of asthma.

Additionally, because high levels of eosinophils can be seen throughout the airways, it can lead to other complications. Research suggests that people with eosinophilic asthma may be more likely to develop other airway conditions, including:

  • middle ear infections
  • nasal polyps
  • sinus disease

It’s important to note that eosinophilic asthma can overlap with other forms, namely allergic asthma.

Eosinophilic and allergic asthma are caused by many of the same inflammatory mechanisms, but allergic asthma is triggered by exposure to a specific allergen, such as pet dander or dust mites. Studies estimate that up to three-quarters of people with eosinophilic asthma also have allergic asthma.

Certain features of your asthma, such as onset during adulthood or the presence of other airway diseases, may lead your doctor to suspect eosinophilic asthma. The diagnosis is confirmed by demonstrating high levels of eosinophils. This can be done by counting cells in either one of the following:

  • blood
  • sputum
  • airway tissues

Diagnosis of eosinophilic asthma is typically done by analyzing blood samples. Sputum samples are typically better for getting an accurate estimate of eosinophilia levels but can be hard to collect unless you are actively coughing up mucus. A lung biopsy is needed to collect airway tissues for sampling; this type of procedure is not usually done in routine practice.

Other tests, including blood tests and lung function tests, may be performed to help support the diagnosis or identify other forms of asthma that may be contributing to symptoms.

Eosinophilic asthma is just one type of asthma. There are many other types that can develop independent of eosinophilia.

Estimates on the presence of eosinophilia in asthma vary widely, and the exact frequency of eosinophilic asthma is unknown. According to one study, about 5% of adults with asthma have eosinophilia, whereas some experts have estimated that up to half of all asthma cases are eosinophilic.

Because eosinophilic asthma increases the likelihood of more severe disease, and because it doesn’t always respond well to certain forms of asthma therapy, it can make it hard to control symptoms.

Chronic, uncontrolled inflammation can damage the tissues in the airways and lungs, leading to worsening asthma symptoms and potentially severe complications such as asthma attacks, emergency department visits, or hospitalization.

Lung damage and breathing problems can also lead to a variety of other complications, including:

  • lung infections
  • sleep problems
  • pregnancy complications
  • gastroesophageal reflux disease (GERD)
  • obesity

People with eosinophilic asthma should work closely with their healthcare teams to ensure their symptoms are optimally controlled and that they are on the right medications to prevent serious complications from their disease.

The American Lung Association offers recommendations to help assess and monitor how well your asthma is controlled and determine whether more supportive care is needed.

Treatment of eosinophilic and non-eosinophilic asthma typically begins the same way. People with either type of asthma are typically prescribed two kinds of medications to help manage symptoms:

  • a controller medication, which is taken long-term to help prevent airway swelling and asthma attacks
  • a quick-relief medication, which is taken as needed to relieve asthma symptoms when they occur

For many people with eosinophilic asthma, standard controller medications don’t work well on their own. Their symptoms may remain uncontrolled, and they may need to use their reliever medications more often than is optimal.

In these cases, your healthcare team may discuss starting an additional medication known as biologic therapy. Biologics used to treat eosinophilic asthma work to lower the levels and effects of eosinophils in the airways to reduce inflammation. A variety of biologics are available to treat eosinophilic asthma, including:

  • benralizumab (Fasenra)
  • dupilumab (Dupixent)
  • mepolizumab (Nucala)
  • omalizumab (Xolair)
  • reslizumab (Cinqair)
  • tezepelumab (Tezpire)

Among these biologics, omalizumab may not be effective in some people with eosinophilic asthma based on its mechanism of action.

Before starting a biologic therapy, your healthcare team will consider a variety of factors, including age, asthma symptoms and severity, and other conditions that may be present.

Eosinophilic asthma is a type of asthma that can be hard to treat, leading to serious complications. People with this form of asthma may benefit from targeted therapies that help treat the underlying eosinophilia that causes airway inflammation and contributes to breathing problems.

If you have been diagnosed with eosinophilic asthma — or suspect you may have this form of asthma based on your symptoms — an asthma specialist can help you understand your diagnosis and identify the treatment option that is right for you.