The Missing Link: Why Allergies and Asthma Often Go Hand in Hand
By Brian Cayko, MBA, RRT
Approximately 25 million Americans suffer from asthma. As you probably know, asthma is a reactive airway disease. This simply means that the smooth muscle and tissues lining the airways of your lungs will react, or overreact, to certain types of stimulants commonly referred to as "triggers."
Allergies affect a reported 50 million people each year in the United States. They come in all shapes and sizes. Some people are allergic to food, animals, the outdoors, and even exercise.
So why is it that we see so many patients with both allergies and asthma? What is the mysterious link between the two diseases?
To answer this question, we only require a basic understanding of what an "allergy" is and then what types of things can cause asthma. But first let's get the 30,000-foot overview of what this looks like.
Simply stated, an asthmatic patient has a predisposed sensitivity that causes the airways to inappropriately narrow in response to some kind of irritant. Normally, a non-asthmatic can be exposed to the same irritant and suffer no consequence, whereas the asthmatic will begin to cough and wheeze as his or her airways tighten.
Now imagine a person who has asthma and is allergic to cats; the cat allergy has now become the perfect irritant to trigger an asthma flare up.
If you do not have asthma you may be exposed to an item that you are allergic to but you wouldn't have the aforementioned respiratory response to it. Sure, you might itch or get watery eyes due to the exposure, but you wouldn't suffer the way an asthmatic would when exposed to that same stimulant.
A closer look
An allergy is when your body's immune system has an inappropriate response to what should normally be a harmless substance. When this happens your body's immune system releases chemicals that trigger your allergy symptoms.
This is typically when we start taking medications to block the release of those chemicals in hopes of reducing our reaction to that exposure. As a person with allergies myself, I understand that this alone is enough to deal with, as I cannot stop sneezing and it feels like the pressure built up in my head is pouring out of every opening of my face as a liquid stream.
But now imagine that you also have asthma. It is estimated that 60-80% of asthmatics also have an allergy, with prevalence of this overlap typically higher in children and young adults than in those over the age of 55.
When this overlap is present the body's chemical response to an allergen becomes the lungs' trigger for inflammation and bronchospasm, leading to the asthma attack.
The missing link
In summary, asthma and allergies are similar in that they are both characterized by an unnatural immune response to an everyday exposure. They even sometimes share a similar body response, such as inflammation, and a common genetic genesis as our bodies form (the missing link); but that's where the connections end.
Allergies do not directly cause a patient to become asthmatic nor does asthma cause a person to be allergic. But they do often overlap due to their similar nature of genetic expression.
Brian Cayko is a member of the American Association for Respiratory Care from Montana, where he serves as director of clinical education for the respiratory care program at Great Falls College MSU.