Tonsillitis is a general term referring to inflammation of tonsillar tissue. Many pathogens can cause tonsillitis (usually associated with acute viral or bacterial pharyngitis) including groups A, C, and G Streptococcus, Fusobacterium necrophorum, Neisseria gonorrhoeae, Corynebacterium diphtheriae, and viral pathogens.

This condition affects both children and adults.

It is usually not possible to determine the etiologic agent responsible for tonsillitis based on symptoms alone. Patients present with tonsillar enlargement and pharyngeal erythema. There may be tonsillar exudate. Rash and lymphadenopathy may also be present. Symptoms usually last for about 1 week.

Diagnostic modalities focus on identifying group A Streptococcus, as antimicrobial treatment is indicated to prevent rheumatic fever. Diagnosis can be made by rapid antigen detection testing or throat culture. Testing for other causes of tonsillitis varies depending on the pathogen suspected.