Bronchitis occurs when the bronchioles (air-carrying tubes in the lungs) are inflamed and make too much mucus.

There are two basic types of bronchitis:

Chronic bronchitis is defined as cough productive of sputum that persists for three months out of the year for at least two consecutive years. The cough and inflammation may be caused by initial respiratory infection or illness, exposure to tobacco smoke or other irritating substances in the air. Chronic bronchitis can cause airflow obstruction and then is grouped under the term chronic obstructive pulmonary disease (COPD).Acute or short-term bronchitis is more common and usually is caused by a viral infection. Episodes of acute bronchitis can be related to and made worse by smoking. Acute bronchitis could last for 10 to 14 days, possibly causing symptoms for three weeks.

Acute bronchitis can be contagious because it is usually caused by infection with a virus or bacteria. Chronic bronchitis is not likely to be contagious because it is a condition usually caused by long-term irritation of airways.

Medications

Because most cases of bronchitis are caused by viral infections, antibiotics aren't effective. However, if your doctor suspects that you have a bacterial infection, he or she may prescribe an antibiotic.

In some circumstances, your doctor may recommend other medications, including:

• Cough medicine. If your cough keeps you from sleeping, you might try cough suppressants at bedtime.
• Other medications. If you have allergies, asthma or chronic obstructive pulmonary disease (COPD), your doctor may recommend an inhaler and other medications to reduce inflammation and open narrowed passages in your lungs.