Is streptococcal tonsillitis contagious?

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Last updated: June 21, 2025View editorial policy

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From the Guidelines

Yes, streptococcal tonsillitis is highly contagious. This bacterial infection, caused by group A Streptococcus bacteria, spreads easily through respiratory droplets when an infected person coughs or sneezes, or through direct contact with infected secretions 1. People with strep throat are typically contagious until they've been on antibiotics for 24-48 hours. The standard treatment is a 10-day course of antibiotics, usually penicillin (such as penicillin V potassium 500 mg twice daily for adults) or amoxicillin (500 mg twice daily for adults, or 50 mg/kg/day divided twice daily for children) 1. For those with penicillin allergies, alternatives include cephalexin, azithromycin, or clindamycin 1.

Some key points to consider:

  • The infection is highly contagious before treatment begins, and patients should take precautions to prevent spreading the infection to others 1.
  • Good hygiene practices like frequent handwashing, not sharing utensils or drinks, and covering coughs and sneezes help limit transmission 1.
  • The bacteria attach to the throat and tonsil tissues, causing inflammation and the characteristic symptoms of sore throat, fever, and swollen tonsils, making the infection easily transmissible before treatment begins 1.
  • Accurate diagnosis of streptococcal pharyngitis followed by appropriate antimicrobial therapy is important for the prevention of acute rheumatic fever and other complications 1.

To prevent spreading the infection, patients should stay home from work or school until fever-free and after taking antibiotics for at least 24 hours 1. It is essential to note that the most recent and highest quality study, which is the 2012 update by the Infectious Diseases Society of America 1, provides the most reliable guidance on the diagnosis and management of group A streptococcal pharyngitis.

From the Research

Contagiousness of Streptococcal Tonsillitis

  • Streptococcal tonsillitis, caused by group A beta-hemolytic streptococci, is a contagious infection 2, 3, 4, 5.
  • The infection can be spread through close contact with an infected person, such as sharing food or drinks, or through respiratory droplets 3, 5.
  • The contagious period of streptococcal tonsillitis is typically until the infected person has been on antibiotic treatment for at least 24 hours 2, 4.

Transmission and Prevention

  • Streptococcal tonsillitis can be prevented by practicing good hygiene, such as washing hands frequently and avoiding close contact with infected individuals 3, 5.
  • Antibiotic treatment, such as penicillin, is effective in reducing the contagious period and preventing the spread of the infection 2, 4, 5.
  • It is essential to complete the full course of antibiotic treatment to ensure that the infection is fully cleared and to prevent the development of antibiotic-resistant bacteria 2, 4, 5.

Diagnosis and Treatment

  • Streptococcal tonsillitis can be diagnosed through a throat culture or rapid antigen detection test 5.
  • Treatment with antibiotics, such as penicillin or macrolides, is effective in reducing the severity and duration of symptoms, as well as preventing complications 2, 4, 5, 6.
  • It is crucial to seek medical attention if symptoms persist or worsen over time, as this can indicate the development of complications or the need for alternative treatment 3, 4, 5.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Macrolides in the management of streptococcal pharyngitis/tonsillitis.

The Pediatric infectious disease journal, 1997

Research

Tonsillitis and Tonsilloliths: Diagnosis and Management.

American family physician, 2023

Research

Streptococcal acute pharyngitis.

Revista da Sociedade Brasileira de Medicina Tropical, 2014

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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