Updated January 29, 2015.
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.
An estimated 25 million Americans suffer from asthma, a chronic lung disease that seems to be 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. The inflammation and subsequent narrowing of the bronchioles results 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, other people may have 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. This is common enough that asthma is often treated by a specialized physician called an Allergist or Immunologist. An Immunologist specializes in the treatment of allergies. An estimated 50% of all asthma cases are cases of allergic asthma.
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 and mold. Most people's body's would deem these substances harmless but for people with allergies, it is recognized as a threat by their immune system. The immune response is activated, including the release of a substance called histamine. Histamine plays an important role in moving white blood cells into our blood vessels but it also causes itching, and swelling. Histamine may contribute to the inflammation of bronchioles in allergic asthma; this is an oversimplification, however, of the immune process, and scientists are still unraveling the exact mechanisms behind allergic asthma. It is clear that if this inflammatory process is ongoing, it can cause sometimes permanent changes to the airways. This is called airway remodeling. The possibility of airway remodeling makes proper treatment of allergic asthma extremely important.
Risk Factors
Some risk factors have been associated with the development of allergic asthma. The presence of risk factors does not insure that a person will develop allergic asthma. It is also true that some people with 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
- virus caused respiratory illness
- obesity
- exposure to dust mites in the first year of life
- some studies have suggested an increased incidence of asthma for individuals who life in urban areas
Avoiding the allergens that trigger an asthma attack is a key part of treating allergic asthma. For more information on removing allergens from your home read: Reducing Allergens in your Home. The use of inhaled corticosteroids to control inflammation is also an important part of treating allergic asthma. Additional inhaled medications may be given for you to use during an asthma attack. Immunotherapy, or allergy shots, is another option for treating allergic asthma.
Sources:
American Academy of Allergy Asthma and Immunology. Asthma. Accessed: January 28, 2015 from http://www.aaaai.org/conditions-and-treatments/asthma.aspx
Asthma and Allergy Foundation of America. Allergic Asthma. Accessed: January 28, 2015 from https://www.aafa.org/display.cfm?id=8&sub=16
Medscape. Allergic and Environmental Asthma Overview of Asthma. Accessed: Januarty 28, 2015 from http://emedicine.medscape.com/article/137501-overview