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Last updated: October 14, 2025View editorial policy

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Differential Diagnosis for Swollen Tonsils

Single Most Likely Diagnosis

  • Viral Pharyngitis: This is the most common cause of swollen tonsils, often due to viruses such as adenovirus, influenza, or the common cold. Symptoms include sore throat, fever, and swollen lymph nodes.

Other Likely Diagnoses

  • Streptococcal Pharyngitis (Strep Throat): Caused by Group A beta-hemolytic streptococcus, this bacterial infection presents with severe sore throat, fever, and swollen tonsils. A rapid strep test or throat culture can confirm the diagnosis.
  • Tonsillitis: Inflammation of the tonsils, which can be caused by either viral or bacterial infections, leading to symptoms like sore throat, difficulty swallowing, and fever.
  • Mononucleosis (Mono): Caused by the Epstein-Barr virus, this condition leads to swollen tonsils, fever, sore throat, and fatigue, often affecting adolescents and young adults.

Do Not Miss Diagnoses

  • Peritonsillar Abscess: A serious complication of tonsillitis where an abscess forms beside the tonsils, causing severe pain, difficulty swallowing, and fever. It requires prompt medical attention, often involving drainage of the abscess.
  • Lemierre's Syndrome: A rare but potentially life-threatening condition that starts with a sore throat and progresses to include a bacterial infection of the jugular vein, leading to symptoms like high fever, neck pain, and swelling.
  • Epiglottitis: Inflammation of the epiglottis, which can be life-threatening if not promptly treated. Symptoms include severe sore throat, difficulty swallowing, and shortness of breath.

Rare Diagnoses

  • Tonsil Cancer: Although rare, cancer of the tonsils can present with swollen tonsils, often accompanied by other symptoms like a sore throat that doesn't go away, difficulty swallowing, or a lump in the neck.
  • Agranulocytosis: A potentially life-threatening reduction in white blood cells, which can lead to severe infections, including those affecting the tonsils. It's a rare side effect of certain medications.
  • Kawasaki Disease: A rare condition that mainly affects children, causing inflammation in the walls of medium-sized arteries throughout the body, and can present with symptoms like swollen lymph nodes, fever, and redness of the throat.

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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