What Is Asthma?

Although it is common to talk about “asthma” as one disease, there are many different types of asthma. All types of asthma involve airway inflammation. However, researchers have found patterns of symptoms and body processes that make up different types of asthma. They hope to find better treatments as they learn more about the different kinds of asthma.

How is asthma classified?

Researchers have only recently started to classify different types of asthma. There are many different ways that this is done. In general, the type of asthma is defined by:

  • Medical history and physical examination
  • Results of lung function tests
  • Age of onset
  • The type of cells involved in inflammation
  • Results of allergy tests
  • Lung and tissue characteristics
  • Response to medications tried in the past

What types of asthma are there?

People use many terms to describe the different types of asthma. Sometimes the terms and categories overlap.

  • Allergic asthma
  • Non-allergic asthma
  • Allergic bronchopulmonary mycosis
  • Aspirin-induced asthma
  • Adult-onset asthma
  • Asthma with fixed airflow obstruction
  • Exercise-induced asthma
  • Eosinophilic asthma
  • Cough-variant asthma
  • Work-related asthma
  • Nighttime (Nocturnal) asthma
  • Asthma with obesity

When and how are types of asthma diagnosed?

Asthma is diagnosed based on symptoms, a physical examination, and lung function tests. Your health care provider will ask about the type and frequency of your asthma symptom and attacks. Tell your provider if you have had eczema, food allergies, hay fever (allergic rhinitis), long-term nasal congestion (chronic rhinosinusitis), heartburn, or reflux in the past.

Inhaled corticosteroids are usually used to treat people with asthma. For some people, these medications do not work well. The first thing to do is to make sure you are taking them properly. If you still have symptoms, more tests may be needed to know which type of asthma you have. The results can help your provider recommend another treatment.


Spirometry is a lung function test used to diagnose asthma. This test checks how much and how quickly you can exhale air. Your provider may ask you to do the test before and after taking a medication that opens the airways (bronchodilator). This test differentiates asthma from other lung diseases.

Allergy testing

Allergy tests can identify people with severe allergic asthma. Inhaled corticosteroids are not as effective for people with severe allergic asthma. If you have severe allergic asthma, you may need medications that make you less sensitive to allergens. Sometimes there is a clear link between allergen and asthma symptoms. In this case, your health care provider may recommend allergy shots.

High eosinophils

Eosinophils are a type of white blood cell. The number of eosinophils increases when people have an allergic disease or infection. High eosinophils are common in allergic asthma, aspirin-induced asthma, and late-onset asthma. Higher eosinophil levels usually indicate more severe asthma. Corticosteroids usually are effective for people with high eosinophil levels. On the other hand, people with few or no eosinophils do not usually respond well to corticosteroids.

Nitric oxide testing

The amount of exhaled nitric oxide is related to the amount of inflammation in the lungs. More nitric oxide indicates more inflammation. Inhaled corticosteroids are usually effective for people with high levels of nitric oxide. People with low levels of nitric oxide may be able to stop taking their corticosteroids.