Acute sinusitis is usually caused by a bacterial or viral infection, or allergic reactions. Commonly, acute sinusitis last up to two weeks. Chronic sinusitis usually lasts a month or longer as the natural healing process of your body was insufficient to treat the condition. Classic symptoms are blocked sinuses, with pain and fever in the case of infection. Read more here on how light therapy can provide relief https://www.photizo.net/za/photizo-sinus/.