What Happens

Asthma often begins during infancy or childhood but may start at any age and last throughout your life. It can increase your risk for complications from lung and airway infections, such as acute bronchitis and pneumonia.

At times, the inflammation from asthma causes a narrowing of your airways and mucus production, resulting in asthma symptoms such as shortness of breath.

The airways narrow when they overreact to certain substances. These are known as asthma triggers and may include:

• Substances you are allergic to (allergens, such as dust mites or animal dander). Allergens cause long-term (chronic) inflammation and may cause asthma symptoms.
• Environmental factors that irritate your airways, such as smoke or cold air. Environmental factors may lead to a tightening of the muscles that line the bronchial tubes (bronchospasm), which can trigger asthma symptoms.

What triggers asthma symptoms varies from person to person. When asthma is triggered by an allergen, it is called allergic asthma.

When asthma symptoms suddenly occur, it is called an asthma attack (also called a flare-up or exacerbation). Asthma attacks can occur rarely or frequently and may be mild to severe. Although some asthma attacks occur very suddenly, many become worse gradually over a period of several days. In general, you can take care of symptoms at home by following your asthma action plan, although a severe attack may require emergency treatment and in rare cases can be fatal.

Asthma is classified as intermittent, mild persistent, moderate persistent, and severe persistent.

• People with intermittent asthma often have symptoms only after being around a trigger.
• People with intermittent asthma usually need medicines only during an asthma attack.
• People with mild persistent or moderate persistent asthma may not always have noticeable symptoms. But they need to take medicines daily to control the long-term inflammation in their airways.
• People with severe persistent asthma have symptoms almost all of the time. Their symptoms need to be treated daily. These people are at increased risk for severe, life-threatening asthma attacks known as status asthmaticus.

Asthma—even mild asthma—may result in changes to the airway system (airway remodeling) and may speed up and make worse the natural decrease in lung function that occurs as we age.³ And some experts believe asthma may raise your risk for chronic obstructive pulmonary disease (COPD).⁴

Sometimes asthma does not respond to treatment because people are not taking their medicines, not taking them correctly, not avoiding triggers, or otherwise not following their asthma action plan. Follow your asthma action plan so you can keep your asthma from getting worse and reduce the risk of death from asthma.

Asthma during pregnancy

Asthma can affect your pregnancy. It may occur for the first time during pregnancy, or it may change during pregnancy.

When asthma is properly controlled, a pregnant woman with asthma can have a normal pregnancy with little or no increased risk to herself or her fetus. But if the asthma is not well controlled, there are risks to the pregnant woman and her fetus. The management of asthma in pregnant women and nonpregnant women is basically the same, although a pregnant woman may need to take different medicines and needs to monitor the fetus's health as well as her own.