Bronchitis is an inflammation of the large bronchi (medium-size airways) in the lungs. It can lead to pneumonia. Acute bronchitis is usually caused by viruses or bacteria and may last several days or weeks.[1] Acute bronchitis is characterized by cough and sputum (phlegm) production and symptoms related to the obstruction of the airways by the inflamed airways and the phlegm, such as shortness of breath and wheezing. Diagnosis is by clinical examination and sometimes microbiological examination of the phlegm. Treatment may be with antibiotics (if a bacterial infection is suspected), bronchodilators (to relieve breathlessness) and other treatments.

Cause/Etiology
Acute bronchitis can be contagious. In about half of instances of acute bronchitis a bacterial or viral pathogen is identified. Typical viruses include respiratory syncytial virus, rhinovirus, influenza, and others.

Acute bronchitis can result from breathing irritating fumes, such as those of tobacco smoke or polluted air.

Signs and symptoms
Bronchitis may be indicated by an expectorating cough, shortness of breath (dyspnea) and wheezing. Occasionally chest pains, fever, and fatigue or malaise may also occur. Additionally, Bronchitis caused by Adenoviridae may cause systemic and gastrointestinal symptoms as well. However the coughs due to bronchitis can continue for up to three weeks or more even after all other symptoms have subsided.

Treatment
Antibiotics
In most cases, acute bronchitis is caused by viruses, not bacteria, and will go away on its own without antibiotics. To treat acute bronchitis that appears to be caused by a bacterial infection, or as a precaution, antibiotics may be given. Also, a meta-analysis found that antibiotics may reduce symptoms by one-half day.

Prognosis
Acute bronchitis usually lasts a few days. It may accompany or closely follow a cold or the flu, or may occur on its own. Bronchitis usually begins with a dry cough, including waking the sufferer at night. After a few days it progresses to a wetter or productive cough, which may be accompanied by fever, fatigue, and headache. The fever, fatigue, and malaise may last only a few days; but the wet cough may last up to several weeks.

Should the cough last longer than a month, some doctors may issue a referral to an otorhinolaryngologist (ear, nose and throat doctor) to see if a condition other than bronchitis is causing the irritation. It is possible that having irritated bronchial tubes for as long as a few months may inspire asthmatic conditions in some patients.

In addition, if one starts coughing mucus tinged with blood, one should see a doctor. In rare cases, doctors may conduct tests to see if the cause is a serious condition such as tuberculosis or lung cancer.

Acute bronchitis may lead to asthma or pneumonia.