Acute rhinosinusitis (ARS) is defined as symptomatic inflammation of the nasal cavity and paranasal sinuses lasting less than four weeks. The term "rhinosinusitis" is preferred to "sinusitis" since inflammation of the sinuses rarely occurs without concurrent inflammation of the nasal mucosa .
The most common etiology of ARS is a viral infection associated with the common cold. Viral rhinosinusitis is complicated by acute bacterial infection in only 0.5 to 2.0 percent of episodes . Uncomplicated acute viral rhinosinusitis (AVRS) typically resolves in 7 to 10 days. Acute bacterial rhinosinusitis (ABRS) also is most commonly a self-limited disease, with 75 percent of cases resolving without treatment in one month. Rarely, patients with untreated bacterial disease may develop serious complications. (See "Orbital cellulitis".)
Distinguishing AVRS related to colds and influenza-like illnesses from bacterial infection is a frequent challenge to the primary care clinician. Antibiotics are indicated for ABRS, but are ineffective and not recommended for AVRS. Despite the overwhelming prevalence of a viral etiology, however, in the late 1990s, 92 percent of patients in the United Kingdom  and 85 to 98 percent of patients in the United States (US)  were prescribed an antibiotic when seen for an upper respiratory or sinus infection. Active initiatives to limit the use of antibiotics for upper respiratory infections are ongoing in Europe and the United States [5,6].
This topic will address the clinical manifestations and diagnosis of acute rhinosinusitis. The treatment of acute rhinosinusitis is discussed separately. (See "Acute sinusitis and rhinosinusitis in adults: Treatment".)
Other topics separately discuss the diagnosis or management of related conditions as follows: