A sinus infection, also referred to as sinusitis, is the result of nasal passages and sinuses becoming inflamed. Causes for a sinus infection include allergies, a viral or bacterial infection, fungi and the use of inhaled illegal substances. Common symptoms of this condition are fever, sore throat, congestion in the nasal area, pressure and pain around the nose, cheeks or eyes, thick greenish or brown phlegm, and a cough. There are a number of over-the-counter products to treat or relieve your symptoms. If the infection is more severe, your doctor may prescribe an antibiotic, which you may have to take up to 2 weeks or more, depending upon how serious your sinus infection is. There are also alternative remedies that address this problem, that can be used in conjunction with conventional treatments.