• Acute sinusitis usually lasts less than 4 weeks and is often triggered by a viral upper respiratory infection (such as a cold).
• Chronic sinusitis lasts 12 weeks or longer and may be associated with ongoing inflammation, allergies, nasal polyps, or other underlying conditions.
• Reduced sense of smell or taste, bad breath, cough (especially at night), and fever can also occur.
• While mucus can be yellow or green, its color alone does not necessarily mean the infection is bacterial.

Medical evaluation is generally recommended if symptoms are severe, last more than about 10 days without improvement, worsen after initially improving, or are accompanied by high fever, significant facial swelling, vision changes, or severe headache.