Asthma

Asthma is a chronic lung disease that inflames and narrows the airways. Asthma causes recurring periods of wheezing (a whistling
sound when you breathe), chest tightness, shortness of breath, and coughing. The coughing often occurs at night or early in the
morning.
Asthma affects people of all ages, but it most often starts during childhood. In the United States, more than 25 million people are
known to have asthma. About 7 million of these people are children.
Overview
To understand asthma, it helps to know how the airways work. The airways are tubes that carry air into and out of your lungs.
People who have asthma have inflamed airways. The inflammation makes the airways swollen and very sensitive. The airways tend
to react strongly to certain inhaled substances.
When the airways react, the muscles around them tighten. This narrows the airways, causing less air to ow into the lungs. The
swelling also can worsen, making the airways even narrower. Cells in the airways might make more mucus than usual. Mucus is a
sticky, thick liquid that can further narrow the airways.
This chain reaction can result in asthma symptoms. Symptoms can happen each time the airways are inflamed.


Sometimes asthma symptoms are mild and go away on their own or after minimal treatment with asthma medicine. Other times,
symptoms continue to get worse.
What Is
When symptoms get more intense and/or more symptoms occur, you're having an asthma attack. Asthma attacks also are called
areups or exacerbations (eg-zas-er-BA-shuns).
Treating symptoms when you notice them is important. This will help prevent the symptoms from worsening and causing a
severe asthma attack. Severe asthma attacks may require emergency care, and they can be fatal.
Outlook
Asthma has no cure.
However, with today's knowledge and treatments, most people who have asthma are able to manage the disease. They have few, if
any, symptoms. They can live normal, active lives and sleep through the night without interruption from asthma.
If you have asthma, you can take an active role in managing the disease. For successful, thorough, and ongoing treatment, build
strong partnerships with your doctor and other health care providers.

The exact cause of asthma isn't known. Researchers think some genetic and environmental factors interact to cause asthma, most
often early in life. These factors include:
An inherited tendency to develop allergies, called atopy (AT-o-pe)
Parents who have asthma
Certain respiratory infections during childhood
Contact with some airborne allergens or exposure to some viral infections in infancy or in early childhood when the immune
system is developing
If asthma or atopy runs in your family, exposure to irritants (for example, tobacco smoke) may make your airways more reactive to
substances in the air.
Some factors may be more likely to cause asthma in some people than in others. Researchers continue to explore what causes
asthma.
The "Hygiene Hypothesis"
One theory researchers have for what causes asthma is the "hygiene hypothesis." They believe that our Western lifestyle—with its
emphasis on hygiene and sanitation—has resulted in changes in our living conditions and an overall decline in infections in early
childhood.
Many young children no longer have the same types of environmental exposures and infections as children did in the past. This
affects the way that young children's immune systems develop during very early childhood, and it may increase their risk for atopy
and asthma. This is especially true for children who have close family members with one or both of these conditions.