sinus treatment http://www.yatan-ayur.com.au/ayurvedic-treatment/diseases-and-treatments/sinusitis Sinusitis is an inflammation of the sinuses. It is often caused by bacterial (germ) infection. Sometimes, viruses and fungi (molds) cause it. People with weak immune systems are more likely to develop bacterial or fungal sinusitis. Some people with allergies can have "allergic fungal sinusitis."