Tonsillitis is inflammation of the tonsils, two oval-shaped pads of tissue at the back of the throat — one tonsil on each side. Signs and symptoms of tonsillitis include swollen tonsils, sore throat, difficulty swallowing and tender lymph nodes on the sides of the neck.
Most cases of tonsillitis are caused by infection with a common virus, but bacterial infections also may cause tonsillitis.
Because appropriate treatment for tonsillitis depends on the cause, it's important to get a prompt and accurate diagnosis. Surgery to remove tonsils, once a common procedure to treat tonsillitis, is usually performed only when tonsillitis occurs frequently, doesn't respond to other treatments or causes serious complications.