Merck Manual

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Acute Bronchitis

By

Sanjay Sethi

, MD, University at Buffalo SUNY

Last full review/revision Jul 2020| Content last modified Jul 2020
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Acute bronchitis is inflammation of the windpipe (trachea) and the airways that branch off the trachea (bronchi) caused by infection.

  • Acute bronchitis is usually caused by a viral upper respiratory tract infection.

  • Symptoms are a cough that may or may not produce mucus (sputum).

  • The diagnosis is based primarily on symptoms.

  • Treatments, such as drugs to reduce fever and cough, may be used to make the person more comfortable until the episode ends.

  • Antibiotics are rarely needed.

Bronchitis can be either

  • Acute

  • Chronic

Acute bronchitis usually lasts days to a few weeks. Bronchitis that lasts for months or years is usually classified as chronic bronchitis. When people say "bronchitis," they usually mean acute bronchitis, and only acute bronchitis is discussed here.

When people with chronic bronchitis have decreased airflow from the lungs when they breathe out (airflow obstruction), they are considered to have chronic obstructive pulmonary disease (COPD). If people who have COPD, or other chronic lung disorders such as bronchiectasis or cystic fibrosis, develop symptoms of acute bronchitis, doctors consider this a flare-up of the underlying disorder rather than acute bronchitis.

Causes

Acute bronchitis is caused by infection due to

  • Viruses (most common)

  • Bacteria

Understanding Bronchitis

In bronchitis, areas of the bronchial wall become inflamed and swollen, and mucus increases. As a result, the air passageway is narrowed.

Understanding Bronchitis

Bronchitis occurs most often during the winter.

Viral bronchitis may be caused by a number of common viruses, including the influenza virus and the viruses that cause the common cold. Even after a viral infection has cleared up, the irritation it causes can continue to cause symptoms for weeks.

Bacteria cause less than one in 20 cases of bronchitis. Mycoplasma pneumoniae, Chlamydia pneumoniae, and Bordetella pertussis infection (which causes whooping cough) are among the bacteria that cause acute bronchitis. Bacterial causes of acute bronchitis are more likely when many people in the same area are affected at the same time (an outbreak).

Cough in adults has many causes besides acute bronchitis. Cough in children has similar causes as in adults.

Symptoms

Infections causing acute bronchitis typically begin with the symptoms of a common cold: runny nose, sore throat, and fatigue. After several days, cough begins (usually dry at first). People may cough up small amounts of thin, white mucus. This mucus often changes from white to green or yellow and becomes thicker. Occasionally, the sputum contains a small amount of blood. Neither the color change nor the presence of blood indicates there is a bacterial infection. Color change means only that cells associated with inflammation have moved into the airway and are coloring the sputum.

People do not usually have a high fever or chills unless the bronchitis was caused by a more serious infection such as influenza.

Did You Know...

  • Coughing up yellow or green-colored sputum does not mean the infection is caused by bacteria.

Because bronchitis can temporarily narrow the airways, people may develop wheezing and/or shortness of breath, similar to what happens in an asthma attack.

Acute bronchitis itself does not cause serious complications. However, some infections that cause bronchitis such as influenza can lead to infection of the lung tissue (pneumonia), usually only in people who are older or who have problems with immune defenses.

Diagnosis

  • A doctor's evaluation

  • Sometimes a chest x-ray

Doctors usually make a diagnosis of acute bronchitis based on the symptoms. Doctors may do a chest x-ray to look for pneumonia if they hear congestion in the lungs, or if people have high or prolonged fever or shortness of breath.

Doctors rarely do tests to find the cause of acute bronchitis, and blood tests are not helpful. However, if a cough persists for more than 2 weeks, a chest x-ray is done to make sure that pneumonia has not developed or a different lung disease is not causing the cough.

Treatment

  • Treatments to relieve symptoms

People may take acetaminophen or ibuprofen to reduce fever and general feelings of illness and should drink plenty of fluid.

Antibiotics do not help viral bronchitis. Since most acute bronchitis is viral, doctors give antibiotics only when the infection is clearly caused by bacteria (for example, during an outbreak). When an antibiotic is used, doctors typically give a drug such as azithromycin or clarithromycin.

Did You Know...

  • Acute bronchitis is usually treated best without using an antibiotic.

In children, very mild symptoms may be helped with cool-mist humidifiers or steam vaporizers. Children and adults who are wheezing may benefit from inhaled bronchodilators, which help open the airways and reduce wheezing.

Cough medicines can be used to suppress a cough that interferes with sleep. However, the degree of effectiveness of these drugs is not clear. Expectorants are over-the-counter drugs that may help thin secretions and make them easier to cough up, but whether this measure is helpful is not clear. Cough suppressants and expectorants are usually not recommended in young children (see also Cough in Children).

Drugs Mentioned In This Article

Generic Name Select Brand Names
BIAXIN
TYLENOL
ZITHROMAX
ADVIL, MOTRIN IB
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