what is sinus

Sinus refers to the air-filled spaces in the face, including the forehead, cheeks, and nose. Sinusitis, also known as a sinus infection, is an inflammation of the tissue lining the sinuses, which can be caused by viruses, bacteria, fungi, or allergies. Sinusitis can cause facial pain, a stuffy or runny nose, and sometimes a fever and other symptoms. Sinus infections are common and usually not serious, and most of them get better on their own without antibiotics. However, in some cases, antibiotics may be needed, and it is best to talk to a doctor about the best treatment for the illness.