What causes tonsillitis?
Most cases of tonsillitis are caused by viruses. For example, the virus that causes mononucleosis (called the Epstein-Barr virus) can cause tonsillitis. Tonsillitis is only caused by bacteria in about 15% to 30% of cases. Bacterial tonsillitis is most often caused by a certain type of streptococcus (or “strep”) bacteria. In these cases, the illness may be called “ strep throat.”
Written by familydoctor.org editorial staff