Understanding Eosinophilic Asthma: Symptoms, Diagnosis, and Treatment Options

Asthma occurs when the airways become inflamed, making it hard to breathe. Symptoms can range from mild to severe and can have many causes. Some people have a type of severe asthma caused by increased levels of specific white blood cells called eosinophils. This subtype of asthma is called eosinophilic asthma, sometimes called eos asthma or e-asthma.

Eosinophilic asthma occurs when there are too many eosinophils in the body. Eosinophils are a type of white blood cell that normally help the body respond to infections and allergens. They can build up in the lungs. The increased number of eosinophils causes inflammation and swelling in the airways, which makes breathing difficult.

Learn more about this condition by visiting EosAsthma.org.

What is the difference between asthma and eosinophilic asthma?

In most forms of asthma, a specific trigger is often the cause, like allergens or exercise. Eosinophilic asthma is caused by swelling in the airways from high levels of eosinophils. It is not always linked to specific allergens or irritants. This can make eosinophilic asthma harder to manage.

Eosinophilic asthma is often more severe. People with high levels of eosinophils in their blood are more likely to have severe asthma attacks.

Is eosinophilic asthma rare?

Eosinophilic asthma is estimated to affect about 5-10% of people with asthma. It is more common in adults than children, and most often presents between the ages of 35 and 50.

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Symptoms of Eosinophilic Asthma

Common symptoms experienced by people with eosinophilic asthma include:

  • Wheezing
  • Coughing
  • Shortness of breath/difficulty breathing
  • Chest tightness
  • Airflow obstruction
  • Swelling in the lining of the nose (nasal mucous membrane)
  • Chronic sinus problems known as chronic rhinosinusitis with nasal polyps (CRSwNP)

These symptoms can make daily life difficult. Even routine tasks or light physical activity may cause breathing problems and discomfort.

Diagnosis of Eosinophilic Asthma

Doctors may diagnose eosinophilic asthma using a series of tests:

  • Blood test: Measures the number of blood eosinophils. High levels of eosinophils in the blood can suggest eosinophilic asthma but can also be a sign of other conditions. 
  • Sputum test: Checks for the number of eosinophils in mucus from a cough.
  • Fractional exhaled nitric oxide (FeNO): Detects airway inflammation.
  • Bronchial biopsy or fluid test: Examines tissue or fluid from the lungs for eosinophils. This is the most invasive test and is usually only done if other tests don’t give enough information.
  • Pulmonary function test: Evaluates lung function

Your doctor may also conduct an allergy test to identify or rule out potential allergic triggers.

If you have eosinophilic asthma, visit with an asthma specialist. Specialists include board-certified allergists or pulmonologists. They can help you manage your symptoms and stay healthy.

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Causes of Eosinophilic Asthma

What causes eosinophilic asthma? It can vary from person to person. The underlying issue for most patients is persistent airway swelling caused by a high number of eosinophils. The swelling is influenced by several factors which lead to asthma symptoms. These factors include:

  • Environmental triggers: Air pollution, tobacco smoke, and workplace exposures can irritate the airways and worsen eosinophilic asthma. Workplace exposures may include dust, chemical fumes, strong cleaning agents, or allergens found in certain jobs, like farming, construction, cleaning, or manufacturing. For example, exposure to pesticides or industrial chemicals can trigger asthma symptoms.
  • Respiratory infections: Colds, the flu, or other infections can cause airway inflammation and worsen asthma symptoms. 
  • Family history: Genetics play an important role in susceptibility to this condition. Having close relatives with asthma or allergies increases your likelihood of developing eosinophilic asthma.

There is also a link between eosinophilic asthma and allergies. People with seasonal or environmental allergies may be more likely to develop inflammation caused by eosinophils. This can lead to the development of eosinophilic asthma.

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Treatment Options for Eosinophilic Asthma

The goal of eosinophilic asthma treatment is to lower the number of eosinophils in your body. This can help reduce inflammation and help you breathe easier.

Many people with eosinophilic asthma respond well to traditional asthma medications. These include:

Short-acting and long-acting beta-agonists (bronchodilators)

Short-acting medications are called quick-relief or rescue inhalers. These medicines quickly relax the muscles around your airways, making it easier to breathe when symptoms emerge suddenly. They are typically used as needed, not every day. Long-acting inhalers offer similar relief of symptoms but are more longer-lasting than quick-relievers.

Inhaled corticosteroids (ICS)

These are controller medicines taken daily. They reduce inflammation (swelling) in your lungs. You breathe the medication in through the inhaler every day to prevent asthma symptoms. It’s important to take inhaled corticosteroids every day, even when you feel well, for long-term asthma control.

Combination inhalers

Some inhalers contain both a short-acting or long-lasting bronchodilator combined with an inhaled corticosteroid. These work together to open the airways, reduce swelling and control symptoms at the same time.

Leukotriene modifiers

These medicines block chemicals called leukotrienes that can make your airways swell and tighten. They come as pills or chewables and can be used along with inhalers.

Oral corticosteroids (OCS)

These are stronger, systemic medications that can quickly reduce inflammation. You can take them by mouth (pills), via injection or IV. They are often used to treat asthma attacks. Doctors only prescribe OCS for short periods (called a “burst”) because long-term use can cause side effects like bone thinning or vision problems.

If you continue to have hard-to-control asthma, or you frequently use OCS for symptoms, talk with your doctor about adjusting your plan for treating eosinophilic asthma. Your doctor may recommend more advanced medications, including biologic therapies.

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Biologics for Eosinophilic Asthma

If your asthma is not well-controlled with inhalers or if you have frequent asthma attacks, your doctor may recommend biologic medications. What is a biologic medication? Biologics are a more targeted therapy designed specifically for moderate to severe asthma. They are injectable medications usually prescribed by specialists like allergists or pulmonologists.

Biologic medications work by targeting the cells and proteins that cause airway inflammation. They stop eosinophils from becoming active and reduce their presence in the body. This can help prevent symptoms and flare-ups.

Biologics provide a personalized approach to care. They are usually prescribed as an add-on therapy, meaning that you can take biologics with other traditional asthma medications. Biologics are given as injections or through an IV, usually every two to four weeks.

Five biologics are approved to treat eosinophilic asthma:

  • Benralizumab (brand name: Fasenra®). This biologic blocks a signal called interleukin-5 (IL-5) by binding directly to the receptor that tells your body to make eosinophils. It reduces inflammation in the airways and helps your immune system clear out eosinophils. The medication is approved for adults and children 6 years and older with severe eosinophilic asthma.
  • Mepolizumab (brand name: Nucala®). This biologic binds directly to the IL-5 signal to block the production of and reduce eosinophils in the blood. It helps reduce eosinophilic inflammation in the airways. The medication is approved for adults and children 6 years and older with eosinophilic asthma.
  • Reslizumab (brand name: Cinqair®). This biologic binds directly to the IL-5 signal to stop the production of and reduce eosinophils in the blood. It helps reduce eosinophilic inflammation in the airways. The medication is approved for adults 18 years and older with eosinophilic asthma.
  • Dupilumab (brand name: Dupixent®). This biologic blocks two signals, IL-4 and IL-13, that cause eosinophilic inflammation. It is approved for adults and children 6 years and older with moderate-to-severe asthma, including eosinophilic asthma or with oral corticosteroid-dependent asthma.
  • Tezepelumab-ekko (brand name: Tezspire®). This biologic blocks a signaling protein called thymic stromal lymphopoietin (TSLP) from binding with a receptor involved in immune responses. It reduces the number of IL-4, IL-5 and IL-13 proteins, as well as levels of eosinophils. The medication is approved for adults and children 12 years and older. It is for severe, uncontrolled asthma regardless of eosinophil level. This makes it an option for both eosinophilic and non-eosinophilic asthma.

A sixth biologic medication for asthma is omalizumab (Xolair®), but it is not indicated for eosinophilic asthma. It is approved to treat severe persistent allergic asthma.

In addition to eosinophilic asthma, biologics are approved to treat a host of respiratory, allergic and skin diseases. These include chronic obstructive pulmonary disease (COPD), atopic dermatitis and chronic rhinosinusitis with nasal polyps (CRSwNP). One of the benefits of biologics is if you have lung disease that is worsened by CRSwNP, for example, these medications are effective at treating both conditions.

Creating a Treatment Plan for Eos Asthma

If you have severe eosinophilic asthma, work together with your doctor to craft a treatment plan. This plan should be tailored to your needs and easy to follow. It should focus on daily management of eosinophilic asthma and what to do if you have an asthma attack.

Getting the right treatment plan is the first step toward controlling your moderate to severe asthma. When your asthma is under control, you can live a healthier, more active life.

Lifestyle changes

While medications play a central role in treating eosinophilic asthma, lifestyle changes can make a meaningful difference. They can complement therapies, helping people with eosinophilic asthma achieve steadier control and fewer severe flare-ups.

Lifestyle changes may include:

  • Trigger awareness and avoidance. Keep track of what makes symptoms worse, such as smoke, air pollution, allergens or strong fragrances. Reducing exposure can help prevent inflammation.
  • Healthy home environment. Using HEPA air filters, washing bedding in hot water, and reducing indoor humidity can cut down on allergens and irritants.
  • Regular exercise. Low- to moderate-intensity activity, like walking, swimming, or cycling, can strengthen lungs and improve endurance. It’s important to warm up properly and use medications as prescribed to prevent exercise-induced flare-ups.
  • Balanced diet. Eating a nutrient-rich diet with plenty of fruits, vegetables, lean proteins, and whole grains supports the immune system. Some studies suggest that diets high in omega-3 fatty acids (found in fish, walnuts, flaxseed) may help reduce inflammation.
  • Weight management. Maintaining a healthy weight can reduce the burden on the lungs and improve asthma control.
  • Stress management. Stress and anxiety can worsen asthma symptoms. Techniques like yoga, meditation, and deep-breathing exercises may help.
  • Regular medical check-ins. Keeping scheduled appointments ensures treatments are adjusted as needed. It can also help track eosinophil levels and lung function over time.

While lifestyle changes should not replace medication, they can greatly improve symptom control and quality of life.

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Management of Eosinophilic Asthma

With the right treatment and regular medical care, most people with eosinophilic asthma can gain better control of their symptoms. They can lead active, fulfilling lives.

Advances in therapy – especially with biologic medications – have made it possible for many patients to breathe easier. They can experience fewer asthma attacks, avoid hospital visits, and reduce or even eliminate the need for oral corticosteroids.

How to Maintain Good Asthma Control

Managing eosinophilic asthma requires ongoing attention. It also requires teamwork between you and your healthcare provider. Here are key steps to help you stay on track:

  • Monitor your symptoms regularly. Keep a diary or use an app to note symptoms. Recognizing early warning signs can help you act before symptoms worsen.
  • Follow your treatment plan. Take medications exactly as prescribed, even when you feel well. Stopping or skipping doses can allow inflammation to return.
  • Avoid known triggers. Common irritants like pollen, mold, pet dander, smoke, and strong scents can cause flare-ups. Try to identify what affects you most and limit exposure when possible.
  • Check in regularly with your doctor. Routine follow-ups allow your healthcare team to adjust treatments, track eosinophil levels, and assess your lung function.
  • Seek care early if symptoms get worse. Prompt treatment can prevent severe attacks and keep you out of the hospital.

Some people with eosinophilic asthma have other inflammatory conditions, such as atopic dermatitis on the skin or chronic rhinosinusitis with nasal polyps, a chronic sinus disease. These conditions share similar immune pathways. Treating both together can make a big difference in controlling symptoms.

With ongoing care, self-awareness, and the right treatment, you can take charge of your asthma and breathe easier every day.

Questions & Answers (Q&As) on eosinophilic asthma

Do you have questions about how to diagnose, manage or treat eosinophilic asthma? Here’s a Q&A with some common questions we’re asked about this condition. If there’s a question you would like to see addressed here, email our editor.

Eosinophilic asthma and allergic asthma are two different types of asthma. Allergic asthma is triggered by allergens like pollen, mold, dust mites, or pet dander. These allergens cause the immune system to react, leading to swelling in the airways.

Eosinophilic asthma is caused by a high number of eosinophils, a type of white blood cell. These cells can cause swelling and narrowing of the airways, making it hard to breathe. Unlike allergic asthma, eosinophilic asthma doesn’t always have clear triggers.

Some people with eosinophilic asthma may also have allergic asthma, which can make their condition worse.

Treatments and management of eosinophilic asthma are different from allergic asthma. Eosinophilic asthma may require certain types of biologics that block or reduce eosinophils. Allergic asthma may require a type of biologic that can stop or reduce allergic reactions. These differences explain why getting an accurate diagnosis is important.

The first step in treating eosinophilic asthma begins with standard asthma inhalers. These can help open the airways and control inflammation.

  • Quick-relief albuterol inhaler: Also called short-acting bronchodilators, these treat sudden symptoms. They quickly relax airway muscles and improve breathing.
  • Inhaled corticosteroids: These are daily controller medications and the cornerstone of asthma treatment. They work by reducing inflammation in the lungs and preventing flare-ups.
  • Long-acting bronchodilators: Sometimes prescribed together with inhaled corticosteroids, these medicines help with asthma control. They relax airway muscles and make breathing easier.

For some people, these treatments may not fully control symptoms, especially when eosinophil levels remain high. In those cases, doctors may add or switch to targeted biologic therapies. These biologics work at the source of inflammation. They can lower eosinophil levels and reduce the risk of asthma attacks.

Yes, inhalers can be used to treat eosinophilic asthma. They can help manage and control symptoms. However, some people may need more advanced treatments. Doctors may prescribe biologics if patients continue to have asthma symptoms despite regular inhaler use.

Biologic medications are a relatively new form of treatment for eosinophilic asthma. These medicines target specific parts of the immune system that cause inflammation. Visit BiologicMeds.org to learn more.

Albuterol is a short-acting beta-agonist (SABA). Albuterol provides quick relief by relaxing the muscles around the airways, making it easier to breathe. While it can relieve symptoms temporarily, it does not treat the underlying inflammation of eosinophilic asthma.

If you are using your albuterol more than two times a week, this may be a sign of uncontrolled asthma. Schedule an appointment with your doctor to discuss a long-term asthma treatment plan.

A phenotype is a set of traits or characteristics that describe how a medical condition appears or behaves. In asthma, the eosinophilic phenotype means that your asthma is linked to high levels of eosinophils – a type of white blood cell involved in inflammation.

To find out if you have this type of asthma, your doctor may order tests to measure eosinophil levels in your blood or in mucus (called sputum) from your lungs. If the results show high eosinophil counts, it suggests these cells are causing inflammation and swelling in your airways. Identifying this phenotype helps your doctor choose the most effective treatment. This includes new targeted biologic therapies designed to reduce eosinophil activity and improve asthma control.

Unlike allergic asthma, eosinophilic asthma is not usually triggered by allergens such as pollen, mold, pet dander, or dust mites. And it typically isn’t caused by exercise. The exact triggers of eosinophilic asthma can be harder to pinpoint and may differ from person to person.

Several factors are known to make symptoms worse or lead to asthma flare-ups, including:

  • Air pollution
  • Poor indoor or outdoor air quality
  • Tobacco smoke or secondhand smoke
  • Workplace irritants such as chemicals, fumes, or dust
  • Respiratory infections like colds or the flu

Because triggers can vary, it’s important to work closely with your doctor to identify what affects you most. Understanding and avoiding your triggers can help you prevent flare-ups and keep your asthma under control.

There are no specific foods to avoid if you have eosinophilic asthma. However, if you also have known food allergies or sensitivities, it’s important to avoid those particular foods. Sometimes a severe allergic reaction can cause asthma symptoms.

Medical treatments are key to treating eos asthma. However, you can also make lifestyle changes to improve your symptoms. They include:

  • Avoiding known triggers: Such as pollutants and irritants.
  • Maintaining a healthy lifestyle: Regular exercise and a balanced diet.
  • Stress management: Practices like yoga and meditation.

Always consult healthcare providers before making significant lifestyle changes.

Eosinophilic asthma can occur at any age. But it is most often diagnosed in adults between 35 and 50 years old. For some eosinophilic asthma patients, it is a type of adult-onset asthma.

Eosinophilic asthma is often associated with severe asthma. Severe asthma is characterized by frequent asthma attacks and persistent symptoms despite standard treatments.

Eosinophilic asthma is a serious health condition. It can cause severe and life-threatening respiratory problems if not well managed. Complications may include frequent hospitalizations and a decline in lung function. This can impact your ability to perform everyday tasks and reduce your quality of life.

Patients with severe asthma can lead normal, active lives with appropriate management. This includes prescribed medications, trigger avoidance, and lifestyle adjustments. Regular follow-ups with doctors are essential.

No, eosinophilic asthma is not an autoimmune disease. Instead, it’s a type of asthma caused by an overactive immune response that leads the body to produce too many white blood cells called eosinophils. When eosinophil levels are high, they cause inflammation and swelling in the airways, making it hard to breathe.

In autoimmune diseases, the immune system mistakenly attacks the body’s own healthy tissues. In eosinophilic asthma, the immune system is overreacting, but it’s not attacking the body. It’s responding too strongly to signals that trigger airway inflammation.

Reviewed by:
William E. Berger, MD, FACAAI, is a board-certified allergist and immunologist who serves as a media spokesperson and Chair of the Medical Advisory Council for Allergy & Asthma Network. He is a Distinguished Fellow and Past President (2002-03) of the American College of Allergy, Asthma & Immunology (ACAAI).