Key Takeaways
- Severe eosinophilic asthma is a subtype of asthma driven by high levels of eosinophils, a type of white blood cell that causes airway inflammation.
- Common signs include frequent flare-ups, persistent coughing or wheezing, and asthma that stays hard to control even with standard inhaler therapy.
- Diagnosis typically involves a blood test for eosinophil counts, sometimes paired with a sputum test or additional lung function testing.
- Eosinophilic asthma is not usually triggered by common allergens like pollen or pet dander, which sets it apart from typical allergic asthma.
- Biologic therapies such as Fasenra, Cinqair, Nucala, Dupixent, and Tezspire may be considered for certain patients whose asthma remains difficult to control with standard treatment.
- Smart Infusion Therapy Services provides biologic infusion and injection therapy for eosinophilic asthma across Wisconsin, and patients can talk to their provider about a referral.
What Makes Eosinophilic Asthma Different
The short answer: eosinophilic asthma is a subtype of asthma caused by elevated eosinophils, white blood cells that drive airway inflammation, rather than by the usual allergic triggers most people associate with asthma. According to the Allergy & Asthma Network, eosinophilic asthma is estimated to affect about 5 to 10 percent of people with asthma, most often appearing in adults between the ages of 35 and 50.
Unlike typical allergic asthma, eosinophilic asthma is not usually set off by pollen, dust mites, pet dander, or exercise. Its triggers can be harder to pinpoint, and it tends to run more severe, with symptoms that persist even on standard treatment.
Common Symptoms and Warning Signs
Eosinophilic asthma often shares symptoms with other forms of asthma, but tends to be more persistent and harder to control:
- Wheezing, including a whistling sound while breathing
- Coughing, especially at night
- Shortness of breath, even during light activity
- Chest tightness or a sense of pressure
- Thick mucus production
- Frequent flare-ups despite regular inhaler use
Some patients with eosinophilic asthma also have related conditions, such as nasal polyps or chronic rhinosinusitis, which can make breathing symptoms feel even more persistent.
Why Some Asthma Patients Continue Having Flare-Ups
Standard asthma inhalers work well for many people, but they may not fully address the inflammation driving eosinophilic asthma. This subtype is linked to a signaling protein called interleukin-5 (IL-5), which promotes the growth and activity of eosinophils in the airway. When IL-5 activity stays high, inflammation can persist even with consistent use of inhaled corticosteroids and other standard controller medications.
This is one reason some patients continue to experience frequent flare-ups, nighttime symptoms, or the need for oral steroid bursts despite doing everything their initial treatment plan recommends.
For certain patients, this ongoing inflammation is also why a specialist may consider targeted biologic therapy rather than simply increasing standard asthma medications.
How Doctors Diagnose Severe Eosinophilic Asthma
Diagnosis generally starts with a review of symptoms and asthma history, followed by testing to measure eosinophil activity:
- Blood test: Measures the number of eosinophils circulating in the blood. Elevated counts can support a diagnosis, though results are interpreted alongside symptoms and history since other conditions can also raise eosinophil levels.
- Sputum test: Looks for eosinophils in mucus coughed up from the lungs. An elevated concentration in mucus samples can point toward this asthma subtype.
- Exhaled nitric oxide testing: A noninvasive breath test that can indicate airway inflammation.
- Lung function tests: Measure how well air moves through the lungs and how asthma is affecting breathing capacity.
Because elevated eosinophils can appear in other conditions as well, a specialist typically considers the full clinical picture, not a single test result, before confirming a diagnosis.
Treatment Options That May Help Improve Control
For patients with confirmed severe eosinophilic asthma, biologic therapies that target IL-5 or related inflammatory pathways have become an important treatment option when standard inhalers are not enough. These medications are designed to reduce eosinophil activity directly, which may help lower the frequency of flare-ups and improve day-to-day symptom control. Options include:
- Anti-IL-5 biologics, such as Cinqair (reslizumab) and Nucala (mepolizumab), which target the IL-5 pathway associated with eosinophilic inflammation
- Anti-IL-5 receptor biologics, such as Fasenra (benralizumab), which targets the IL-5 receptor on eosinophils
- Dupixent (dupilumab), which targets IL-4 and IL-13 signaling and may be used for moderate-to-severe asthma with an eosinophilic phenotype
- Tezspire (tezepelumab), which targets thymic stromal lymphopoietin (TSLP), an inflammatory signaling protein involved earlier in the asthma inflammatory pathway
Because these medications target different parts of the inflammatory process, having severe asthma does not automatically mean one specific biologic is the right choice. An allergist or pulmonologist typically compares these options based on eosinophil levels, symptom pattern, other biomarkers and health conditions, and treatment history before recommending one.
How Smart Infusion Therapy Services Supports Eosinophilic Asthma Patients
Smart Infusion's immunology infusion programs include biologic therapies used to treat severe eosinophilic asthma, administered in a private outpatient setting. Asthma therapies available through Smart Infusion include Cinqair, Fasenra, and Tezspire, giving eligible patients access to both infusion and injection-based biologic treatment options. Compared with a hospital-based infusion suite, many patients find the clinic experience calmer, with shorter waits and more consistent scheduling. The care team also helps coordinate insurance verification and prior authorization, and communicates with referring allergists and pulmonologists to keep treatment aligned over time.
Patients who want to learn more about specific options can also read Smart Infusion's educational resources on Fasenra for severe asthma and comparisons such as Tezspire versus Fasenra.
Talk to Your Provider About a Referral to Smart Infusion
If your asthma symptoms keep returning despite following your treatment plan, it may be worth asking your doctor about eosinophilic asthma and whether testing makes sense for you. Identifying the right asthma subtype is often the key to finding a treatment that actually improves control.
If a biologic therapy such as Fasenra, Cinqair, or Tezspire is part of your asthma care plan, talk to your provider about a referral to Smart Infusion Therapy Services for treatment across Wisc
Frequently Asked Questions
How do I know if I have eosinophilic asthma?
Signs that may point to eosinophilic asthma include frequent flare-ups, persistent coughing or wheezing, and asthma symptoms that stay hard to control despite regular inhaler use. A blood or sputum test measuring eosinophil levels, ordered by your doctor, is typically needed to confirm the diagnosis.
What eosinophil count is considered high for asthma?
There is no single universal cutoff, but many specialists consider blood eosinophil counts at or above 300 cells per microliter to be clinically significant in adults with asthma, since research has linked this level to more frequent exacerbations. Your doctor will interpret your specific results alongside your symptoms and history.
Is eosinophilic asthma the same as allergic asthma?
No. Eosinophilic asthma is often not triggered by common allergens like pollen, dust mites, or pet dander, and it is not typically triggered by exercise either. That said, some patients have both allergic asthma and elevated eosinophils, so a specialist evaluation helps clarify the full picture.
Are there infusion clinics in Wisconsin that treat severe asthma?
Yes. Smart Infusion Therapy Services offers infusion clinics in Eau Claire, Wausau, Madison, and Onalaska, Wisconsin, providing biologic therapy for severe eosinophilic asthma.
