Tonsillitis is an infection of the tonsils at the sides of your throat that can cause a sore throat, problems swallowing, a high temperature and more. Learn how to treat tonsillitis yourself, when to see a GP or call 111, and what complications to look out for. Tonsillitis is an infection of the tonsils caused by viruses and bacteria. When tonsillitis occurs the tonsils get inflamed and swell up causing nasal obstruction and/or breathing, swallowing, and sleep problems. Tonsillitis is a condition that causes inflammation and irritation of the tonsils , often due to viral or bacterial infections. Learn about the common signs of tonsillitis, such as sore throat, fever, and white spots on the tonsils , and the best ways to treat it, including medications and tonsillectomy. Tonsillitis Tonsillitis is a common condition that happens when your tonsils get infected. Symptoms typically include sore throat, fever and swollen lymph nodes. Treatment depends on whether the infection is viral or bacterial, and recovery usually takes about one week.