Sinus infection, often known as sinusitis, is a common condition that causes the sinuses to expand. Inflammation of the sinuses causes symptoms similar to those of a regular cold. In reality, a sinus infection can develop after a cold or the flu. Sinusitis affects almost 31 million people in the United States, with over $1 billion spent on treatment each year. You can, however, attempt several inexpensive and efficient natural remedies for sinus infections.