The update group made strong recommendations that clinicians (1) should distinguish presumed ABRS from acute rhinosinusitis (ARS) caused by viral upper respiratory infections and noninfectious conditions and (2) should confirm a clinical diagnosis of CRS with objective documentation of sinonasal inflammation, which may be accomplished using anterior rhinoscopy, nasal endoscopy, or computed tomography. The update group made recommendations that clinicians (1) should either offer watchful waiting (without antibiotics) or prescribe initial antibiotic therapy for adults with uncomplicated ABRS; (2) should prescribe amoxicillin with or without clavulanate as first-line therapy for 5 to 10 days (if a decision is made to treat ABRS with an antibiotic); (3) should reassess the patient to confirm ABRS, exclude other causes of illness, and detect complications if the patient worsens or fails to improve with the initial management option by 7 days after diagnosis or worsens during the initial management; (4) should distinguish CRS and recurrent ARS from isolated episodes of ABRS and other causes of sinonasal symptoms; (5) should assess the patient with CRS or recurrent ARS for multiple chronic conditions that would modify management, such as asthma, cystic fibrosis, immunocompromised state, and ciliary dyskinesia; (6) should confirm the presence or absence of nasal polyps in a patient with CRS; and (7) should recommend saline nasal irrigation, topical intranasal corticosteroids, or both for symptom relief of CRS. The update group stated as options that clinicians may (1) recommend analgesics, topical intranasal steroids, and/or nasal saline irrigation for symptomatic relief of viral rhinosinusitis; (2) recommend analgesics, topical intranasal steroids, and/or nasal saline irrigation) for symptomatic relief of ABRS; and (3) obtain testing for allergy and immune function in evaluating a patient with CRS or recurrent ARS. The update group made recommendations that clinicians (1) should not obtain radiographic imaging for patients who meet diagnostic criteria for ARS, unless a complication or alternative diagnosis is suspected, and (2) should not prescribe topical or systemic antifungal therapy for patients with CRS.