What is the most common cause of tonsillitis?

The most common cause of tonsillitis is a viral infection, while some cases are caused by bacteria such as group A streptococcus. Symptoms can overlap, so a sore throat alone cannot identify the cause.

Tonsillitis may cause swollen, red tonsils, throat pain, fever, tender neck glands and difficulty swallowing. Cough, runny nose or hoarseness can occur with a viral illness. Strep throat may be more likely when throat pain begins suddenly with fever and swollen glands, but examination and testing may be needed. Earache can occur because throat inflammation shares nearby nerve pathways.

Rest, drink fluids and choose soft foods while swallowing is uncomfortable. A GP consultation can assess the throat and decide whether testing or antibiotic treatment is appropriate. Antibiotics do not treat viral infections and should only be taken when prescribed. Avoid sharing cups and wash hands often while symptoms are active.

Seek urgent help for difficulty breathing, inability to swallow saliva, drooling, severe one-sided throat pain, a muffled voice, neck swelling or inability to open the mouth normally. Arrange review if fever persists, symptoms worsen, dehydration develops or episodes keep returning.

Ask whether the pattern suggests a viral infection or strep throat, whether a throat test is needed, how to manage pain safely, and which changes should prompt urgent reassessment.