What is the most common cause of acute bronchitis?

What is the most common cause of acute bronchitis?

• A. Bacterial
• B. Viral
• C. Fungal
• D. Unknown

Answer: (B)

Acute bronchitis is most often caused by viral infections. After an upper respiratory viral illness, viruses such as rhinovirus, influenza, or RSV inflame the bronchial lining, leading to a persistent cough that can last days to weeks. This viral origin explains why the chest exam and imaging are typically unremarkable and why antibiotics—targeting bacteria—usually don’t help in the typical case. Bacterial, fungal, or unknown etiologies occur much less frequently in uncomplicated acute bronchitis, making the viral cause the best explanation for most presentations.

Acute bronchitis is most often caused by viral infections. After an upper respiratory viral illness, viruses such as rhinovirus, influenza, or RSV inflame the bronchial lining, leading to a persistent cough that can last days to weeks. This viral origin explains why the chest exam and imaging are typically unremarkable and why antibiotics—targeting bacteria—usually don’t help in the typical case. Bacterial, fungal, or unknown etiologies occur much less frequently in uncomplicated acute bronchitis, making the viral cause the best explanation for most presentations.