What is the most common cause of acute sinusitis?

Acute sinusitis is most commonly caused by a viral infection. This understanding stems from the fact that the majority of cases associated with sinusitis follow a viral upper respiratory infection, such as the common cold. When a viral infection occurs, it can lead to inflammation and swelling of the sinus mucosa, restricting proper drainage and creating an environment conducive to fluid accumulation. This fluid can promote further complications, including bacterial infections.

While bacterial infections can occur and are more likely to develop as a secondary consequence of initial viral infections, they are not typically the primary cause of acute sinusitis. Allergic reactions can exacerbate sinus issues but are not a direct cause of acute sinusitis. Fungal infections are rare in healthy individuals and are more commonly associated with chronic sinus issues, making them less prevalent in cases of acute sinusitis. Thus, recognizing the role of viruses in triggering acute sinusitis is crucial for understanding its commonality and managing treatment effectively.