The Asthma and Allergy Connection

Anyone with both allergies and asthma can tell you that these conditions are closely related. Scientists are still unraveling the exact mechanisms of this phenomenon, here's what we know.

Symptoms of Asthma

An estimated 25 million Americans are living with asthma, a chronic lung disease that is more common in children but occurs in people of all ages. The incidence of both allergies and asthma has been increasing worldwide in recent years.

Asthma causes inflammation of the bronchioles, the small tubes that carry air into the lungs.

Inflammation and subsequent narrowing of the bronchioles result in the symptoms of asthma, which include:

• Coughing
• Wheezing
• Chest tightness
• Difficulty breathing

The symptoms of asthma are associated with several triggers. Some people experience symptoms only when exercising, some people experience symptoms when they are exposed to chemical fumes such as gasoline, and other people may have allergic asthma.

Allergic Asthma

Allergic asthma is what some medical professionals call asthma that is brought on when an individual is exposed to something they are allergic to. An estimated 50% of all asthma cases are cases of allergic asthma. This is common enough that asthma is often treated by a specialized physician called an Allergist-Immunologist. These doctors specialize in the treatment of allergies.

To understand the association between allergies and asthma it may also help to know something about the physiology of an allergic reaction. An allergen is a substance that triggers an allergic reaction.

In allergic asthma, the allergen is usually inhaled,

Common culprits include:

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

These substances are generally harmless, but for people with allergies, they are considered a threat by their immune system.

The immune response is activated, including the release of a substance called histamine. Histamine causes dilation of blood vessels, which allows fluid to exit blood vessels and move into surrounding tissue which causes swelling. Histamine also causes localized itching. White blood cell move from inside the blood vessels into surrounding tissue through the effects of chemokines and inflammatory markers on vascular endothelium, not as a result of histamine.

Histamine may contribute to the inflammation of bronchioles in allergic asthma, and scientists are still unraveling the exact mechanisms behind allergic asthma.

If this inflammatory process is recurrent, it can sometimes cause permanent changes to the airways. This is called airway remodeling. 

Risk Factors

Some risk factors have been associated with the development of allergic asthma. The presence of risk factors does not ensure that a person will develop allergic asthma and some people who have allergic asthma may not have any of the associated risk factors.

Risk factors that have been associated with allergic asthma may include:

• A family history of allergies or allergy-related illnesses
• Obesity
• High exposure to dust mites in the first year of life
• Some studies have suggested an increased incidence of asthma for individuals who live in urban areas

Avoiding the allergens that trigger an asthma attack is a key part of managing allergic asthma. The use of inhaled corticosteroids to control inflammation is also an important part of treating allergic asthma. You might also be prescribed or given additional inhaled medications during an asthma attack.

Once your asthma is under good control, immunotherapy, or allergy shots, are sometimes added on to treat environmental allergies that may be associated.