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Published on: 7/21/2026
Tonsillitis is often contagious when caused by a viral or bacterial infection. Viral tonsillitis typically remains contagious for 7 to 10 days, while bacterial cases (such as strep throat) can spread for about 2 weeks untreated, or until 24 hours after starting antibiotics.
Because contagious periods and treatment needs vary widely depending on the underlying cause, guessing can delay recovery and put others at risk. Take a free, instant, online symptom check to better understand what may be causing your sore throat and get clear guidance on your next steps.
Reviewed for medical accuracy: 07/20/2026
Tonsillitis is an inflammation of the tonsils, often due to infections. It can be caused by viruses or bacteria, making it contagious. If it is due to a bacterial infection, like streptococcus, it can be contagious until 24 hours after starting antibiotics. For viral causes, it may stay contagious for as long as symptoms are present.
Here are some key points:
Infections like infectious mononucleosis are also contagious and can cause tonsillitis. This type of infection might stay contagious for a longer period, even weeks.
If you're experiencing symptoms and want to better understand what might be causing them, try our free AI symptom checker to get personalized insights. It's important to maintain good hygiene, like washing hands and avoiding close contact, to prevent the spread of tonsillitis.
(References)
Casey JR, & Pichichero ME. (2005). Higher dosages of azithromycin are more effective in .... Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, 15909262.
Dalalah D, & Magableh S. (2008). A remote fuzzy multicriteria diagnosis of sore throat. Telemedicine journal and e-health : the official journal of the American Telemedicine Association, 18817494.
Dunmire SK, Hogquist KA, & Balfour HH. (2015). Infectious Mononucleosis - PubMed - NIH. Current topics in microbiology and immunology, 26424648.
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