A sinus infection, also known as sinusitis, occurs when the cavities around the nasal passages become inflamed or swollen. This inflammation can be caused by infections, allergies, or other factors, leading to symptoms such as nasal congestion, facial pain, and a runny nose. Sinus infections can be acute, lasting for a short time, or chronic, persisting for several weeks or longer. Treatment often includes rest, hydration, and over-the-counter medications to relieve symptoms. In some cases, a doctor may prescribe antibiotics if a bacterial infection is suspected.