Sinusitis is an inflammation of the sinuses, which are air-filled spaces located in the skull. This condition can occur when the sinuses become blocked due to infections, allergies, or other factors. Symptoms often include nasal congestion, facial pain or pressure, and a reduced sense of smell. There are two main types of sinusitis: acute and chronic. Acute sinusitis typically lasts for a short period, often following a cold, while chronic sinusitis can persist for months or even years. Treatment options may include medications, such as decongestants or antibiotics, depending on the underlying cause.