Foul smells found in the sinus cavity come from a sinus infection, an inflammation or swelling of the sinuses. Normally, sinuses are filled with air, but a sinus infection causes fluid entrapment inside a sinus blockage. Bacterial growth within that fluid is the source of the foul odor, states WebMD.
Sinus infection symptoms, such as fever or cough, headache, nasal obstruction, or a thick, yellow sinus discharge, may develop with a cold. If symptoms persist after 10 days, individuals should visit a physician for treatment. Other symptoms of a sinus infection include pressure or pain around the eyes and face, headache, and post-nasal drip, WebMD explains.
Sinus infections occur after other conditions, such as nasal polyps, allergies and non-allergic rhinitis, block the nasal passages. Anatomical abnormalities, such as a deviated septum, may prolong sinus infection symptoms. A deviated septum is a nasal cavity shift that blocks off the sinus cavity and traps fluid, states WebMD.
Diagnosis of a sinus infection occurs during a physical exam and involves a review of a person's medical history. Initial treatment involves taking prescription antibiotics and then decongestants. If the medication is ineffective, an X-ray or CT scan may be ordered. Home treatment of a sinus infection, such as steamy showers, may be prescribed to alleviate painful symptoms, such as sinus and nasal swelling, according to WebMD.