Streptococcal Pharyngitis (Group A Beta-Hemolytic Streptococcus): This is the most common bacterial cause of pharyngitis, especially in children and young adults. Repeat episodes could be due to incomplete treatment, resistance, or recurrent exposure.

Viral Pharyngitis: Many viruses can cause pharyngitis, including adenovirus, influenza, and rhinovirus. Repeat episodes are common due to the high prevalence of viral infections.
Tonsillitis: Inflammation of the tonsils, which can be caused by both viral and bacterial pathogens, leading to recurrent pharyngitis.
Allergic Rhinitis: Postnasal drip from allergic rhinitis can cause chronic or recurrent pharyngitis.

Lemierre's Syndrome: A rare but potentially life-threatening condition caused by Fusobacterium necrophorum, leading to sepsis and thrombophlebitis of the internal jugular vein. It presents with severe pharyngitis and can be fatal if not promptly treated.
Epiglottitis: Inflammation of the epiglottis, which can cause severe pharyngitis and potentially life-threatening airway obstruction.
Diphtheria: A bacterial infection caused by Corynebacterium diphtheriae, which can lead to severe pharyngitis and is preventable with vaccination.
Mononucleosis (Infectious Mononucleosis): Caused by Epstein-Barr virus, it can present with severe pharyngitis and has potential complications such as splenic rupture.

Gonococcal Pharyngitis: Caused by Neisseria gonorrhoeae, it's a rare cause of pharyngitis but important to consider in sexually active individuals.
Tuberculous Pharyngitis: A rare manifestation of tuberculosis that can cause chronic pharyngitis.
Syphilitic Pharyngitis: Caused by Treponema pallidum, it's a rare cause of pharyngitis but should be considered in individuals with risk factors for sexually transmitted infections.
Fungal Pharyngitis: More common in immunocompromised patients, it can be caused by various fungi, including Candida species.