Q. I have asthma. Can you explain how bronchodilators and steroids help me breathe easier?
A. To understand how asthma medications work, you need to understand how asthma affects your lungs.
Asthma assaults the lung's airways. The airways are the tubes through which the air you breathe enters and leaves your lungs. During an asthma attack, the airways get narrower as the muscles surrounding them constrict. During an attack, the airways also become inflamed. Mucus produced by the inflammation fills the narrowed passageways. As a result, the flow of air is partially or completely blocked. (I've put an illustration of this on my website, AskDoctorK.com.)
Some people with asthma have only occasional, mild symptoms. These might include wheezing, difficulty breathing or a persistent cough. Others have nearly constant symptoms with severe, life-threatening flare-ups. Symptoms of a severe asthma attack can include extreme shortness of breath, chest tightness, flared nostrils, pursed lips, and bluish lips and fingernails.
Asthma medicines fall into two general categories: controllers and relievers. Controllers are medicines taken regularly (usually every day) to reduce the likelihood of asthma attacks. Relievers are used just during asthma attacks, to stop or reduce the severity of the attack.
Whether controllers or relievers, asthma medications act in one of two ways: (1) they prevent or stop inflammation of the airways; (2) they relax the muscles that line the airways.
• Bronchodilators relax the muscles around the airways to improve airflow. The most common types of bronchodilators are the beta agonists. There are both long-acting types and short-acting types. The long-acting types are controllers: They are used to reduce the number of asthma attacks and are usually prescribed for daily use. The short-acting types are relievers, used to stop an asthma attack, whether mild or severe.
Bronchodilators can be inhaled in an inhaler or taken with a nebulizer, a device that mixes medications with a mist for inhalation.
• Anti-inflammatory medications prevent asthma attacks from happening. They are usually taken regularly, regardless of whether you are having symptoms. They work by reducing inflammation, which decreases mucus production and reduces tightening of airway muscles.
Anyone with asthma symptoms that occur more than a couple times per week should consider taking an anti-inflammatory medication. The first choice is usually an inhaled corticosteroid.
• Other medications: Drugs called methylxanthines are older types of controllers; they work mainly on relaxing the muscles of the airways. Drugs called leukotriene inhibitors are newer types of anti-inflammatory drugs that are controllers. A drug called ipratropium sometimes is used in the emergency room during severe attacks to relax the airways. An anti-inflammatory drug called omalizumab is a controller that can effectively reduce the number of serious attacks in some people.
Fortunately, we have better treatments for asthma today than we did when I trained to become a doctor. If you take your medications as prescribed, you will minimize the effect asthma has on your life.
• Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com.