Eosinophilic Asthma Diagnosis & Treatment
About 10% of people diagnosed with asthma have a type called severe asthma. Patients with severe asthma have harder-to-control symptoms including shortness or breath, coughing, wheezing or chest tightness. These symptoms are sometimes hard to control eve with medicine.
Some people have a type of severe asthma called eosinophilic asthma (eos asthma). This is diagnosed when your body makes too many white blood cells called eosinophils (ee-oh-SIN-oh-fills). Eosinophilic asthma may require special treatment to help control symptoms and lower the number of eosinophils.
Your doctor can diagnose eos asthma using simple tests. Getting the right diagnosis helps your doctor choose the best treatment to manage your asthma. With proper treatment, you can breathe easier, control asthma attacks, and keep doing the things you love.
How is eosinophilic asthma diagnosed?
Most people with eosinophilic asthma are diagnosed based on testing, symptoms and family history. Healthcare providers use different tests to determine if you have eosinophilic asthma. Here are the primary tests:
Blood test
- The test will help measure the number of eosinophils in your blood.
- People with eosinophilic asthma usually have high numbers (at least 150 cells per microliter, but often over 300).
How the blood test is performed:
- A doctor or nurse takes a small amount of blood from your arm (a blood draw).
- This test is quick and simple. It is often done at your doctor’s office or at a clinical lab.
- Your doctor will examine your blood eosinophil levels, asthma symptoms and health history to make the diagnosis.
Sputum sample examination
- The test helps determine how many eosinophils are in your mucus (sputum).
- If 2-3% (or more) of the cells in your mucus are eosinophils, you might have eosinophilic asthma.
How the sputum test is performed:
- You cough up a small mucus sample.
- Your sample is looked at under a microscope and the eosinophils are counted. This will help determine, along with health history, if you have eosinophilic asthma.
Bronchial biopsy or bronchial fluid examination
If blood and sputum tests don’t clearly show what’s causing your symptoms, or if your asthma is severe or doesn’t respond to treatment, your doctor may recommend a bronchial biopsy to learn more. This test can help:
- Confirm if your airways have elevated levels of eosinophils.
- Rule out other causes of symptoms, like infections or other lung diseases.
- Guide your doctor in choosing the right treatment plan.
How the bronchial biopsy is performed:
- A lung specialist (an allergist or pulmonologist) does a procedure called a bronchoscopy.
- The lung specialist carefully inserts a thin, flexible tube (bronchoscope) into your lungs through your nose or mouth.
- The specialist gathers small samples of lung tissue or fluid.
- You might get medicine to help you relax or sleep during the test.
- Most times, a bronchial biopsy is done as an outpatient test, and most people go home the same day.
Treating eosinophilic asthma
The primary goal of eosinophilic asthma treatment is to lower the number of eosinophils in your body. This can help you breathe easier and reduce asthma symptoms. Many patients with eosinophilic asthma respond well to traditional asthma medications. But if you continue to have hard to control symptoms, your doctor may move you up a step by adjusting your treatment plan to include more advanced medications. These include injectable biologics.
Eosinophilic asthma medications
Here are the main types of medications used for eosinophilic asthma treatment:
Bronchodilators (short-acting or long-acting beta-agonists)
Short-acting medications are called quick-relief or rescue inhalers. These medicines are called albuterol or levalbuterol. They quickly relax the muscles around your airways, making it easier to breathe. Quick relievers work fast to relieve symptoms like coughing, wheezing, and shortness of breath. They are used as needed to treat sudden symptoms and can also pre-treat asthma prior to exercise.
Long-acting medications offer similar relief of symptoms but are more longer-lasting than quick-relief inhalers.
Inhaled corticosteroids (anti-inflammatory medicines)
These daily controller medicines reduce inflammation (swelling) in your lungs. You breathe the medication in through an inhaler every day to prevent the start of asthma symptoms. It’s important to take these consistently 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 and reduce swelling at the same time. This can help control daily symptoms and prevent asthma attacks.
Leukotriene modifiers
These medicines block chemicals called leukotrienes that can make your airways swell and tighten. They come as pills or chewables and can beused 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”). Long-term use can lead to severe side effects like bone thinning, diabetes, weight gain or vision problems.
Biologic therapies
If traditional asthma medications are not working well, or you often need oral corticosteroids for treatment, your doctor may recommend biologics. Biologics are special, injectable medicines that target specific parts of the immune system, including eosinophils, to help reduce inflammation and prevent flares.
Biologics for eosinophilic asthma
Biologics are medications that work deep within your immune system, at the level of individual cells. They belong to a group of medicines called monoclonal antibodies. These are lab-made proteins designed to target very specific parts of the immune system that drive airway inflammation.
By calming this overactive immune response, biologics can help reduce asthma attacks and improve breathing. They are usually prescribed for people with moderate to severe asthma, especially when standard inhalers aren’t enough to keep symptoms under control.
Biologics are often prescribed to treat eosinophilic inflammation (as well as other allergic diseases). They can help lower the number and halt production of eosinophils in the body.
Biologics are given as an injection every few weeks. Some must be administered in your doctor’s office (so your care team can monitor you after the first dose), while others can be self-injected at home once you are trained. Work together with your doctor to decide which biologic and injection schedule best fit your needs.
Here are the biologics approved in the United States to treat eosinophilic asthma (as of October 2025):
Benralizumab (brand name: Fasenra®)
- Benralizumab 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.
- It is given via an auto-injector. The first three doses are given every 4 weeks. Then, you receive one shot once every 8 weeks. You can give it at home after the first dose.
- The medication is approved for adults and children 6 years and older with severe eosinophilic asthma.
- It is an add-on treatment for severe eosinophilic asthma. It’s also approved for eosinophilic granulomatosis with polyangiitis.
Mepolizumab (brand name: Nucala®)
- Mepolizumab 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.
- It is given as an injection every four weeks. You can take it at home after the first dose.
- The medication is approved for adults and children 6 years and older with eosinophilic asthma.
- It is an add-on treatment for severe eosinophilic asthma. It’s also approved for eosinophilic granulomatosis with polyangiitis, hypereosinophilic syndrome and chronic obstructive pulmonary disease (COPD).
Reslizumab (brand name: Cinqair®)
- Reslizumab 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.
- It is given by IV (through a vein), usually at a clinic or hospital. A health professional can administer it at your home.
- The medication is approved for adults 18 years and older with eosinophilic asthma.
- It is an add-on treatment with other asthma medications.
Dupilumab (brand name: Dupixent®)
- Dupilumab blocks two signals, IL-4 and IL-13, that cause eosinophilic inflammation.
- It is given as a shot every two weeks. Most people are able to take it at home after the initial dose.
- The medication is approved for adults and children 6 years and older with moderate-to-severe asthma, including eosinophilic asthma or with oral corticosteroid-dependent asthma.
- Dupilumab is an add-on maintenance therapy. It’s also approved for COPD, eczema, eosinophilic esophagitis (EoE), chronic sinusitis with nasal polyposis, and chronic spontaneous urticaria.
Tezepelumab-ekko (brand name: Tezspire®)
- Tezepelumab works by blocking 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.
- Tezepelumab is given as an injection once every four weeks.
- It is indicated for use in adults and children 12 years and older who have severe, uncontrolled asthma.
- Tezepelumab can be used to treat any type of severe asthma. This includes 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.
At-home management of eosinophilic asthma
Managing eosinophilic asthma every day can help you feel better and avoid flare-ups. Along with your treatment plan, there are things you can do at home to better manage your asthma.
Self-management tools and tips::
- Use a symptom tracker to write down your asthma symptoms. This helps you and your doctor see how well your treatment is working.
- Follow your Asthma Action Plan every day. This plan tells you what medicine to take and what to do if symptoms get worse.
- Avoid known triggers like smoke, strong smells, or dust if those make your asthma worse.
- Stay active with light exercise (as approved by your doctor) and get plenty of sleep. Pre-treat with albuterol if recommended by your doctor.
If you also have allergic asthma, consider these tips:
- Clean your home regularly to eliminate or reduce allergens like dust mites, mold or pet dander.
- Use an air purifier and keep doors/windows closed during allergy season to avoid pollen and pollution.
- Wash bedding weekly in hot water to help keep dust mites away. Do not hang laundry outside when there are high pollen counts.
Working with specialists to manage eosinophilic asthma
Managing eosinophilic asthma can require teamwork. Work closely with primary care doctors, nurses, physician assistants, and asthma specialists who understand this type of asthma. These healthcare providers can help find the right treatments, track your symptoms, and adjust your care plan when needed.
If you need help finding a doctor who treats eosinophilic asthma, check out this resource from APFED.
How do doctors decide on eosinophilic asthma treatment?
If you are diagnosed with eosinophilic asthma, your doctor will create a treatment plan tailored to your symptoms, lung function and lab results. Because eos asthma is driven by eosinophils, the goal is to reduce these levels, calm airway inflammation and prevent flare-ups.
Here’s what doctors consider:
- Reviewing your history and symptoms. They’ll ask how often you cough, wheeze, or feel short of breath, and whether you’ve had recent asthma attacks or ER visits.
- Checking eosinophil levels and other tests: A blood test (and sometimes a sputum or nasal sample) helps measure eosinophils. Lung function tests show how well you’re breathing.
- Assessing current medications. Doctors look at how you’re using inhaled corticosteroids and bronchodilators, and whether doses are high enough.
- Adding advanced therapy if needed. If symptoms remain despite standard inhalers, your doctor may suggest a biologic that targets the cells or signals driving eosinophilic inflammation. These injections can reduce attacks and steroid use.
- Managing related conditions. Treating nasal polyps, sinus disease, or allergies can make asthma easier to control.
- Follow-up and adjustment. Treatment is reviewed regularly. If your asthma improves, your doctor may adjust doses; if not, they’ll explore other options.
Finding a specialist who treats eos asthma
People with moderate to severe asthma may need to see a specialist, such as a board-certified allergist or pulmonologist. These doctors have advanced training in diagnosing, managing and treating asthma with the most effective medications.
Specialists can prescribe advanced treatments, like biologic medicines. They are often more up-to-date on the latest options available to patients. Working with a specialist can help you get the care you need sooner and keep your asthma under better control.
To learn more about accessing care or finding a specialist near you, check out
APFED’s eosCARE program and the Specialist Finder.
Preparing for your doctor’s appointment
Get ready before your appointment so you feel more confident and can make the most of your time with the doctor. Bringing the right information helps your doctor understand how your asthma is doing and what changes may be needed.
Here is how to prepare:
- Track your symptoms. Write down how often you have asthma symptoms, what triggers them (if any), and if they wake you up at night. Use the Rules of TWO® or your Asthma Action Plan to check your control level.
- List your medications. Include all asthma medicines you take. How often you take them. If they are helping or not.
- Bring questions. Don’t be afraid to ask! Write down anything you’re unsure about or want to learn more about. This will help you not forget anything during the checkup.
- Know your insurance. Make sure you know what treatments and medicines are covered by your health plan. This can help you and your doctor decide what options work best for you. Learn more about health insurance for asthma.
Tools to help you prepare for your checkup
- You can find helpful tools like checklists and worksheets to bring to your appointment on APFED’s eosCARE site.
- For help understanding insurance or how to get coverage for asthma treatments, check out Insurance Essentials.
Asthma Action Plan, Rules of TWO® and Self-Management Tools
If you have asthma symptoms a lot or feel like the condition is keeping you from everyday activities, your asthma might not be under control. That’s a sign you should speak up, work with your care team, and make a plan.
One way to check your asthma control is by using the Rules of TWO®. This simple tool helps you know when quick-relief medicine isn’t enough. It also helps you know when it’s time to talk to your doctor about changing your treatment plan.
| Rules of Two |
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| Rules of TWO® When is quick relief for asthma NOT ENOUGH? DO YOU....  ✓ Take your quick relief inhaler more than TWO TIMES A WEEK? ✓ Awaken at night with asthma more than TWO TIMES A MONTH? ✓ Do you refill your quick-relief inhaler more than TWO TIMES A YEAR? ✓ Use prednisone TWO or more times a year for flares of asthma? Measure changes in peak flow with asthma symptoms of more than TWO TIMES 10 (20%)? If you answer "yes" to any of them, talk to your doctor. Rules of Two is a registered trademark of Baylor Health Care System |
What is an Asthma Action Plan?
An Asthma Action Plan is a written document that guides you on how to manage your asthma and what to do when your symptoms get worse. It helps you:
- Know which medicine to take and when
- Track your symptoms and peak flow
- Know when to call your doctor or get emergency help
You and your doctor can create this plan together.
Questions and Answers (Q&A) about how to treat eosinophilic asthma
Eosinophilic asthma treatment often requires more advanced medical care. Here are some common questions we’re asked about eosinophilic asthma treatment along with their answers. If there’s a question you feel should be added, please email our editor.
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).
