Sinusitis or sinus infection occurs when the sinuses, air-filled cavities behind the forehead, nose, and cheeks, are inflamed and swollen. The main causes can be fungus, bacteria, or viruses. These elements cause congestion in the sinuses and result in many health issues. Along with cortisone, steroids like prednisone can help alleviate swelling and inflammation in people with this condition. Most people would use prednisone in the form of nasal sprays. Nevertheless, your healthcare provider would suggest an injection when your sinus infection persists for more than 3 months or does not respond to other treatment options.