Allergic Versus Nonallergic Asthma

Asthma is sometimes divided into 2 types depending on whether you have allergies. These types are allergic (or extrinsic) asthma and nonallergic (or intrinsic) asthma. In allergic asthma, symptoms are triggered by exposure to an allergen. In nonallergic asthma, symptoms are not linked to allergies.^1,2

We now know of more subtypes and overlapping types of asthma. But it is still helpful to know whether your asthma is allergic or nonallergic. This can help you manage symptoms and prevent asthma attacks. Allergic asthma may respond better to medicines. We need more research to know how the type of asthma affects treatments and outcomes.^3,4

How are allergic and nonallergic asthma different?

People with allergic and nonallergic asthma have the same symptoms. This includes wheezing, coughing, and trouble breathing. The main differences between allergic and nonallergic asthma are what causes symptoms and when symptoms start.²

Allergic asthma is the most common type. About 60 percent of people with asthma have it. Common features of allergic asthma include:^1,2,5

• Symptoms starting during childhood
• Symptoms triggered by exposure to allergens
• Past or family history of allergic conditions, such as:
  • Eczema
  • Hay fever (allergic rhinitis)
  • Food allergies
• A positive reaction to skin allergen testing

Nonallergic is less common. Between 10 percent and 33 percent of people with asthma have it. Common features of nonallergic asthma include:^5,6

• Symptoms starting during adulthood
• Symptoms not linked to allergen exposure
• A negative reaction to skin allergen testing

What causes allergic and nonallergic asthma?

In allergic asthma, symptoms are linked to allergen exposure. Some common triggers of allergic asthma include:²

• Cockroaches
• Dust mites
• Mold
• Pet dander
• Pollen

When you are exposed to these triggers, your body reacts as if the trigger was something harmful. Your immune system tries to fight off the allergen. It releases a protein called immunoglobulin E (IgE). IgE causes immune cells to release inflammatory chemicals. This leads to airway inflammation and asthma symptoms.^4,7

In nonallergic asthma, symptoms are not linked to allergen exposure. It may not be possible to identify the trigger. Common triggers of nonallergic asthma include:⁶

• Cold or dry air
• Heat and humidity
• Air pollution
• Smoke
• Chemicals and fumes
• Fragrances
• Stress and anxiety
• Exercise
• Respiratory infections
• Hormonal changes
• Medicines

We do not know why exposure to these triggers leads to asthma symptoms. Experts think the immune system reacts in a different way than in allergic asthma. This may lead to different types of inflammation.^5,6

We also do not know why some people develop allergic or nonallergic asthma. A history of allergic conditions seems to increase the risk of allergic asthma. Genetics also play an important role in developing asthma.²

How are allergic and nonallergic asthma diagnosed?

Doctors diagnose allergic and nonallergic asthma in similar ways. They will use symptoms, physical exams, and spirometry. Spirometry is a type of breathing test. It measures how much air you breathe in and out of your lungs.^1,3

Test results that may suggest you have allergic asthma include:^1,3

• High levels of exhaled nitric oxide
• High levels of white blood cells called eosinophils
• Positive skin prick allergy tests
• Positive IgE blood tests

An allergist can help determine which allergens are your triggers. If they do not find that any allergens are triggers, you may have nonallergic asthma. Your doctors can then help you figure out what else may be triggering your symptoms.⁶

How are allergic and nonallergic asthma treated?

Treatments for allergic and nonallergic asthma are similar. They may involve a combination of:^2,6

• Daily controller drugs, such as inhaled corticosteroids
• Quick-relief rescue drugs, such as short-acting beta-agonists
• Lifestyle changes
• Avoiding triggers

Doctors will follow a stepwise approach to treating either type of asthma. This means they will increase or decrease your treatments based on how well they work. This can include changing your dosage or suggesting alternative medicines.¹

Certain treatments work better to manage allergic asthma. People with allergic asthma benefit more from allergen shots and biologics. People with allergic asthma may respond better to inhaled corticosteroids.^1,3