Viral Pharyngitis: This is the most common cause of sore throat and is often accompanied by a low-grade fever. It is usually self-limiting and caused by viruses such as rhinovirus, coronavirus, or adenovirus.

Streptococcal Pharyngitis (Strep Throat): Caused by Group A beta-hemolytic streptococcus, this condition presents with sore throat, fever, and can be differentiated from viral pharyngitis by a rapid strep test or throat culture.
Influenza: Especially during flu season, influenza can cause sore throat, fever, and other systemic symptoms like body aches and cough.
Mononucleosis (Mono): Caused by Epstein-Barr virus, mono can present with sore throat, fever, fatigue, and lymphadenopathy, especially in young adults.

Epiglottitis: A potentially life-threatening condition that can cause severe sore throat, difficulty swallowing, and high fever. It requires immediate medical attention.
Lemierre's Syndrome: A rare but serious condition that starts with pharyngitis and can progress to sepsis and jugular vein thrombosis, typically caused by Fusobacterium necrophorum.
Retropharyngeal Abscess: A collection of pus in the tissues in the back of the throat, which can cause severe throat pain, difficulty swallowing, and fever, and requires prompt medical intervention.

Diphtheria: A bacterial infection that can cause a sore throat and a membrane to form over the tonsils and throat, though it is rare in areas with high vaccination rates.
Tuberculosis (TB): Can cause chronic sore throat and fever among other symptoms, especially in immunocompromised individuals or those exposed to TB.
Syphilitic Pharyngitis: A manifestation of primary syphilis, which can cause a sore throat and other systemic symptoms, particularly in individuals with high-risk sexual behavior.