Intrinsic (Nonallergic) Asthma

Most people with asthma have allergic asthma. It is brought on by certain known allergens that are identifiable. But if your asthma is triggered by factors other than allergens, like extreme weather or a respiratory infection, you may have nonallergic asthma.¹

Allergic vs nonallergic asthma

Asthma is a lung condition resulting from inflamed airways which narrow causing a decrease in the amount of air that gets into the lungs. It can bring on wheezing, coughing, and tightness in the chest. Two asthma subtypes are extrinsic (allergic) and intrinsic (nonallergic).^1,2

Extrinsic asthma develops in response to allergens, such as dust mites, pollen, and mold. It is the most common form of asthma according to the Asthma and Allergy Foundation of America.^1,2

Intrinsic is less common, representing from 10-33% of asthma cases. Nonallergic asthma often develops in adults and is more common in women.² This kind of asthma also has multiple triggers some of which include stress, extreme heat or cold, exercise, and infections. Other triggers may not be easily identified.^1-3

The symptoms and treatment of intrinsic and extrinsic asthma are generally the same; it is the causes and prevention strategies that differ.^1-3

What causes nonallergic asthma?

Figuring out which triggers affect you can be difficult. Sometimes no known cause can be identified. Nonallergic asthma develops when something other than an allergen triggers the immune system to respond by releasing antibodies that cause inflammation.²

Intrinsic or nonallergic asthma can be caused by:^2,3

• Cold or dry air
• Heat and humidity
• Air pollution
• Smoke
• Chemicals and fumes
• Fragrances
• Stress
• Anxiety
• Strenuous exercise
• Respiratory infections or viruses
• Hormonal changes
• Some medications

The underlying reasons for developing nonallergic asthma are not well understood. Researchers continue to study a combination of genetic and environmental factors which play a role in the development of asthma.³

How is it diagnosed?

An asthma diagnosis is made based on symptoms, a physical examination, and a variety of tests. Asthma is most commonly triggered by allergens, a reaction to pollen, mold, dust mites, pet dander, and more.¹ There are standard blood and skin tests used by allergists to test for allergic reactions that can lead to an asthma attack. These are usually negative for people with nonallergic asthma.^1-3

Because asthma can be triggered by factors other than allergies, most people seek input from an allergist. An allergist can help determine the triggers associated with breathing difficulty.¹ When there are no allergens causing the asthma attack, other triggers need to be considered. You may be asked to keep a journal of symptoms related to where you were and what you were doing prior to an asthma episode.³

How is it treated?

Asthma symptoms are characterized by breathing difficulties. Wheezing, coughing, shortness of breath, and increased mucus production are some of the main symptoms. Nonallergic asthma is treated in much the same way as allergic asthma.^1-3

Treatment options include medications, lifestyle changes, and the avoidance of triggers. Avoiding triggers is a reasonable first step in treating allergic asthma. However, it may be more difficult to do with nonallergic asthma; especially if the triggers are unknown.²

Medications are available to treat all kinds of asthma. There are short and long-acting acting ones that provide different kinds of relief. Some prevent an attack before it begins (long-acting) others provide relief for an attack already in process (short-acting).^2,3

Lifestyle changes can be effective in reducing asthma flare-ups and reducing symptoms. Some suggestions include:^1-3

• Reduce stress
• Don’t smoke
• Avoid secondhand smoke, smog and pollution
• Avoid strong smells and cleaning products
• Maintain a healthy weight
• Get a flu vaccine
• Keep clean hands clean to reduce risk of infection

Will nonallergic asthma go away?

There is no cure for asthma. So, in most cases, asthma does not go away. There are steps to take to manage asthma so that flare-ups occur less often. This is true for both allergic and nonallergic subtypes.² Intrinsic asthma can be more difficult to control when the triggers are unknown.^1-3