Allergic Asthma: A Common Type of Asthma

Allergic asthma, or extrinsic asthma, is the most common form of asthma. Of the 20 million Americans with asthma, more than seven million adults and three million children suffer from allergic asthma.

Allergic asthma results from an allergic reaction. Ordinarily, your immune system exists to fight off infection. In allergic asthma, however, your body senses allergens—which would normally be harmless—as foreign and mounts an attack against them. This immune attack can lead to asthma symptoms.

But not all asthma is allergic. Another form of asthma is sometimes referred to as intrinsic asthma. While the symptoms that you experience are not any different, the causes of intrinsic asthma are not yet entirely understood.

The triggers for allergic and intrinsic asthma are the same, however. An infection (viral illness) or some type of irritant, such as an indoor pollutant like cleaning products or tobacco smoke, can aggravate both types of asthma. Other common triggers can include weather changes, strong odors, or outdoor pollutants like ozone. Patients with intrinsic asthma will not test positive on allergy tests or have elevated IgE levels.

Allergic Asthma Symptoms

Many of the symptoms of allergic asthma and non-allergic asthma are the same and include:

• Wheezing
• Chest tightness
• Shortness of breath
• Chronic cough

Allergic asthma symptoms can be triggered by:

• Tobacco smoke
• Animal dander
• Dust mites
• Cockroaches
• Molds
• Pollens

In general, allergic asthma is triggered when you inhale one of the previously mentioned triggers. Once you inhale these triggers, a complex reaction (referred to as the pathophysiology of asthma) begins, resulting in the development of asthma symptoms. Much of this results from the development of IgE.

IgE, Your Immune System, and Allergic Asthma

Normally your immune system protects you from infections, but it can also be responsible for your worsening symptoms in allergic asthma. You may notice that at the same time you have allergy symptoms such as a runny nose, watery eyes, and other sinus complaints, your peak flows are lower, you are wheezing more, and you experience more shortness of breath. So, how is the immune system and allergic asthma linked?

If you have allergic asthma then you are most likely atopic and have an inherited a predisposition toward allergies. As a result, your immune system develops an exaggerated response to the previously mentioned allergens or triggers.

Your body senses these allergens, perceives them as foreign, and prepares to fight them off as a foreign invader. This process, often referred to as the allergic cascade, occurs in three steps:

1. Sensitization—First exposure to an allergen causing the development of IgE.
2. Early phase response—Upon re-exposure to an allergen, IgE now binds to the allergen, which causes the release of other chemicals, called mediators (such as histamine), that cause acute inflammation and bronchoconstriction.
3. Late phase response—Release of eosinophils after binding of allergen and IgE causes more inflammation and symptoms several hours after the exposure, as well as the production of additional allergic chemicals such as leukotrienes.

In summary, your body is exposed to an allergen which causes your body to develop IgE. On re-exposure to that allergen, IgE leads to the development of asthma symptoms.

Treating Allergic Asthma

Allergic asthma treatment primarily involves three main components:

1. Monitoring of peak expiratory flow and asthma symptoms
2. Avoidance of your allergic asthma triggers
3. Treatment with medications

You can also go a long way to reducing your exposure to allergic asthma triggers by:

• Reducing moisture
• Decreasing dust mites
• Making your bedroom a trigger-free zone