What is Asthma?

By: Edwin A Bronsky, MD
Last Reviewed on: April 26, 2005
The word "asthma" brings to mind different thoughts for different people. Some people think of asthma as just a "breathing problem"?rarely requiring a trip to the doctor or emergency room. If you suffer from asthma, this word probably brings episodes of breathlessness to mind. Or if you are a family member, it may mean that a loved one is uncomfortable, ill, or living a disrupted life, regularly missing school or work. To physicians who treat asthma, it is a serious medical condition that kills approximately 5,000 people each year in the U.S. Anyone can feel the loss in the quality of life brought about by asthma.

How Is Asthma Recognized?
Medically, asthma is a name assigned to a group of symptoms that includes shortness of breath, wheezing, coughing, and chest tightness. These symptoms can occur in various combinations (one, several, or all) and may range from mild to severe. Symptoms are usually intermittent, perhaps happening only on rare occasions or seasonally; some people go for a long period without symptoms and then suddenly have severe episodes for days at a time. Others have weekly or daily asthma attacks, while in the most severe cases, symptoms are present at all times.

The most common asthma symptom recognized by both physicians and patients is wheezing, a whistling sound that's created when air passes through the narrowed breathing tubes that mark asthma. Wheezing, which may be very loud or barely audible, is usually most obvious during exhalation. Asthmatics also have difficulty inhaling during an attack, which causes the feeling of shortness of breath (dyspnea). Also, mucus that normally forms in the airways cannot be easily cleared, which triggers coughing. Unfortunately, each of these underlying changes eventually contributes to and aggravates other asthma symptoms, like chest tightening.

Are There Different Types of Asthma?
There are various types of asthma, some of which are difficult to diagnose. Further complicating accurate diagnosis is that in certain individuals, there are very specific, unique patterns of symptoms.


Cough-variant asthma
Coughing can occur alone, without the other symptoms of asthma that are usually present and recognized by the physician or patient. Cough-variant asthma is tough to diagnose because it can be easily confused with other conditions, such as chronic bronchitis and postnasal drip. Coughing can occur day or night. Nighttime coughing may be most disruptive, as it interferes with sleep. Nocturnal asthma

When nighttime asthma occurs without any daytime symptoms, It's called "nocturnal asthma." People with the condition may have wheezing or trouble breathing when lying down, or may not notice these symptoms until awoken by them--typically between 2 a.m. and 4 a.m. Nocturnal asthma may occur only once in a blue moon or frequently during the week. Nighttime symptoms are also a common problem for people who have daytime asthma. If this is the case, then nocturnal symptoms are more easily recognized and confirmed. However, when there are no daytime symptoms to suggest asthma is the underlying cause of nighttime woes, this type of asthma will be more difficult to recognize. The cause (or causes) of nocturnal asthma is unknown, although many possibilities are under investigation.

Exercise-induced asthma
Shortness of breath and/or wheezing occurring after strenuous exercise is called exercise-induced asthma. Although this phenomenon happens in up to 80 percent of people with recognized asthma, it is frequently an isolated event, without symptoms at any other time. This complicates any diagnosis of asthma as an underlying cause because it is frequently confused with poor physical conditioning or possible heart problems. Nevertheless, asthma should always be suspected as a possible cause of exercise-induced wheezing or shortness of breath, especially when the person is otherwise healthy and in shape.

What Causes Asthma?
Asthma symptoms were once thought to arise solely from spasms of the bronchial tubes (airways). But in the 1980s, experts began to recognize bronchial tube inflammation as the basic underlying problem. Inflammation is part of the immune system's response to injury or harmful foreign substances that enter the body. Inflammation is caused by the arrival of blood cells and other immune system sentries into the area involved. In people with allergies, this defense system reacts against normally benign substances like pollen from weeds and trees.

Is asthma an "allergic" condition? Not always, but certain allergens (any substance that can spur an allergic reaction) are common triggers of asthma symptoms. These include dust mites, cockroaches, molds and pollens.


With asthma, the allergen triggers an unwanted inflammatory reaction in the airways. Certain immune cells release chemicals called mediators that attack the allergen and, along the way, set off asthma symptoms.

During this defensive act, some damage and changes occur in the tissues of the bronchial tubes, which can cause them to become easily irritated, or "hyper-responsive." In this state, the lungs become excessively "twitchy" and may react (or overreact) to previously non-stimulating irritants, such as cold weather, pollution, dry air, and chemical odors.

This entire process is possibly reversible if caught early and addressed with preventive measures, like avoidance or appropriate medication. If left untreated these changes in the lungs and airways can lead to long-term, irreversible damage. Numerous scientific studies have shown that avoidance of specific allergens will result in less severe asthma symptoms and less medicine.

In summary, we now recognize asthma as a disease that involves inflammation and eventual hyper-reactivity in the bronchial tubes, all of which manifests in the wheezing, coughing and breathlessness of an asthma attack. By learning to recognize the underlying factors and symptoms of asthma, we as physicians and patients can more adequately control and better treat both the causes and effects of asthma.