Non-eosinophilic asthma is a type of severe asthma without elevated eosinophil levels. Typical asthma treatments are usually ineffective for people with this type of asthma.

Non-eosinophilic asthma (NEA) is a type of severe asthma. Also known as non-type-2 severe asthma, NEA is characterized by poor responses to conventional asthma treatments. Unlike eosinophilic asthma (EA), high eosinophil levels are absent upon testing.

Keep reading to learn more about NEA, including its causes, symptoms, and outlook. We’ll also review current and emerging treatment options for this severe type of asthma.

What are eosinophils?

Eosinophils are types of white blood cells. It’s typical for your white blood cell count to be made up of 0.5–1% eosinophils. Higher levels than this are often present in allergies, asthma, and other immune-related conditions.

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NEA is characterized by severe airway inflammation.

Eosinophils do not contribute to the inflammation in this type of severe asthma. Instead, different white blood cell buildups, changes in airway smoothness, and lifestyle factors are among the possible risk factors.

To better understand the causes, we can break NEA down into subtypes:

Neutrophilic asthma

Neutrophilic asthma is a type of NEA due to a buildup of neutrophils in your body. Like eosinophils, neutrophils are white blood cells usually present in small amounts.

Neutrophils are smaller and don’t survive as long as eosinophils. Their main job is to protect against bacterial and fungal infections, while eosinophils primarily protect against parasites.

However, too many neutrophils can cause severe airway inflammation.

Paucigranulocytic asthma (PGA)

PGA is a subtype that doesn’t typically consist of individually elevated neutrophils or eosinophils. Instead, you may have mixed granulocyte cells, which include a combination of white blood cells such as neutrophils, eosinophils, and basophils.

Even though PGA is the most common subtype in both adults and children whose asthma symptoms are “stable,” one 2018 review notes that it’s not responsive to corticosteroids like other types of NEA.

Obesity-related late-onset asthma

Obesity-related late-onset asthma is an NEA subtype seen in adults who develop asthma later in life and who also have obesity.

According to a related 2021 study, while researchers don’t know the long-term effects of obesity on asthma, adults with both conditions may be at a higher risk of respiratory-related hospitalizations.

Possible risk factors for NEA include:

The symptoms of NEA consist of uncontrolled asthma symptoms that don’t respond to inhaled corticosteroids or other treatments. This is similar to all types of severe asthma.

A doctor may determine you have uncontrolled asthma if you experience the following:

  • wheezing, chest tightness, and other asthma symptoms that develop during the daytime more than twice per week
  • having to use quick-relief asthma medications, such as a rescue inhaler, more than twice per week
  • nighttime asthma symptoms that wake you up more than twice per month
  • symptoms that are severe enough to interfere with your regular activities

There are two main types of severe asthma: type-2 inflammation and non-type-2 inflammation.

Type 2 inflammation asthma includes EA, which is due to excess eosinophils, and allergic asthma. NEA, on the other hand, is a form of non-type-2 inflammation.

Aside from presenting with signs of uncontrolled asthma, diagnosing NEA involves multiple tests. Among these include:

  • a mucus (sputum) sample to look for the presence of eosinophils or neutrophils
  • blood or skin tests that measure immunoglobin antibodies and rule out possible allergic asthma
  • breathing tests
  • tests for comorbidities, such as GERD

There’s no single treatment yet available for NEA, and treatments for other forms of asthma don’t usually work for this subtype.

However, emerging treatments may be available to target NEA subtypes better. These include:

A non-drug option might be bronchial thermoplasty, which involves applying targeted heat to the airways in your lungs.

A doctor may also recommend lifestyle modifications, such as weight loss, quitting smoking, and reducing acid reflux.

Severe asthma itself is rarely deadly. However, due to the lack of effective treatments for NEA, people with this type of asthma may experience more exacerbations and hospitalizations than those with other subtypes.

Like other cases of uncontrolled asthma, NEA can also disrupt your daily activities and quality of life. This may be due to persistent symptoms and medication side effects.

Consider the following questions you may consider further discussing with a doctor about NEA, including its causes, outlook, and treatment.

What can trigger non-eosinophilic asthma?

Many NEA triggers are similar to those of severe asthma in general. These include environmental triggers, such as pollen, mold, and air pollution. Other triggers include smoking, infections, and obesity.

How common is non-eosinophilic asthma?

Experts estimate that 5–10% of people with asthma have severe forms. This includes NEA. Up to 50% of severe asthma cases may be NEA.

While it’s not clear exactly how many people have NEA, researchers do know that NEA is not as common as other types of asthma, such as allergic asthma.

Is eosinophilic asthma more serious than non-eosinophilic asthma?

Both EA and NEA are severe types of asthma. While doctors consider both to be serious, NEA may be more challenging to treat.

Eosinophils often play a role in the development of severe asthma. But in about half of severe asthma cases, eosinophil levels are not elevated. Non-eosinophilic asthma (NEA) may be more challenging to treat because it doesn’t respond to long-term controller medications or inhaled corticosteroids.

Still, emerging treatments appear to be on the horizon for NEA. In addition to new therapies, a doctor may also recommend lifestyle changes that may help address comorbidities that often exacerbate NEA symptoms, such as GERD or obesity.