Bacterial or viral infections of the respiratory tract
Viral illnesses are the most common cause of upper respiratory symptoms. Symptoms of a viral illness often appear over several hours without prior illness. Common viral illnesses include colds and the flu (influenza).
Bacterial respiratory tract infections are less common than viral infections. Bacterial infections may develop after a viral illness such as a cold or the flu. Bacterial infections may affect the upper or lower respiratory system, and symptoms tend to localize to one area.
Your lungs work hard -- most adults take more than 20,000 breaths a day. But just how well your lungs do their job may be affected by the job you do. Chemicals. Germs. Tobacco smoke and dirt. Fibers, dust, and even things you might not think are dangerous can damage your airway and threaten your lungs. "The lungs are complex organs," Philip Harber, MD, MPH, professor of public health at the Mel and Enid Zuckerman College of Public Health at the University of Arizona in Tucson, tells WebMD. "Occupational...
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The most common sites of bacterial infections in the upper respiratory system are the sinuses and throat. Pneumonia is the most common bacterial infection of the lower respiratory system.
Antibiotics are effective against bacterial infections only after they have developed, so most health professionals do not prescribe them until a bacterial infection is suspected or confirmed.
WebMD Medical Reference from Healthwise
