In this article, we discuss the causes, symptoms, and treatment of intrinsic and extrinsic asthma.

The symptoms of these subtypes are the same, but they have different triggers:

Asthma is a chronic lung condition in which the airways narrow and become inflamed, which leads to wheezing, coughing, and chest tightness. Extrinsic asthma and intrinsic asthma are subtypes of asthma.

Intrinsic and extrinsic asthma are two subtypes of asthma, which people more commonly refer to as allergic and nonallergic asthma.

Both types cause the same symptoms. The difference between the two subtypes is what causes and triggers asthma symptoms. The treatments are similar for each type, although the prevention strategies differ.

Triggers

Share on Pinterest Intrinsic and extrinsic asthma have the same symptoms but different triggers.

In people with extrinsic asthma, allergens trigger the respiratory symptoms. Common triggers for extrinsic asthma include:

pollen

mold

dust mites

pet dander

cockroaches

rodents

In some cases, a person is allergic to more than one substance, and several allergens trigger asthma symptoms.

In people with intrinsic asthma, allergies are not responsible for the symptoms. Instead, the following triggers cause symptoms:

cold

humidity

stress

exercise

pollution

irritants in the air, such as smoke

respiratory infections, such as colds, the flu, and sinus infections

In some cases, intrinsic asthma can occur with no known cause.

Prevalence

Extrinsic or allergic asthma is the most common form of the disease. According to the Asthma and Allergy Foundation of America, about 60% of people with asthma have allergic asthma.

Less commonly, intrinsic or nonallergic asthma occurs. Research in The Journal of Allergy and Clinical Immunologyindicates that intrinsic asthma occurs in anywhere from 10% to 33% of people with asthma.

It occurs more often in females than males and typically develops later in life than extrinsic asthma.

Causes

In all types of asthma, a person has overly sensitive airways and airway inflammation, which produces asthma symptoms.

Inflammation causes swelling in the airways that narrows the tubes and makes breathing difficult. The body also produces excess mucus, which further impairs breathing. These factors decrease the amount of air that can get into the lungs.

The inflammatory processes are similar in extrinsic and intrinsic asthma. In both, the immune system releases cells called T-helper cells and mast cells.

Research has found that there may be more similarities between the two types of asthma than researchers previously thought. Both types of asthma involve the production of IgE locally at the airways in response to the relevant triggers: