What is the most common cause of acute bronchitis?

The most common cause of acute bronchitis is viral infections, primarily rhinovirus. Acute bronchitis typically occurs following a viral upper respiratory infection, and rhinovirus is one of the main viruses responsible for this type of infection. The inflammation of the bronchial tubes that characterizes bronchitis is often initiated by the body's immune response to the viral infection, leading to symptoms such as cough, mucus production, and difficulty breathing.

In many cases, additional viruses like the influenza virus or coronavirus can also contribute to acute bronchitis, but rhinovirus is the most frequently identified pathogen in these infections. It's notable that while bacterial infections can occasionally occur, they are less common in the initial stages of acute bronchitis, especially since the condition is primarily viral in nature.

Factors like allergic reactions and environmental pollutants may contribute to bronchial irritation or exacerbate symptoms, but they do not generally cause acute bronchitis on their own. Understanding the viral etiology highlights the importance of recognizing the seasonality and transmission patterns of respiratory viruses, which can aid in prevention and management strategies for acute bronchitis.