Odynophagia

Infectious esophagitis: Candida, herpes simplex virus (HSV), cytomegalovirus (CMV)
Pill-induced esophagitis: NSAIDs, KCl, AZT, alendronate, iron, antibiotics
Caustic esophageal injury (alkali or acid ingestion)
Radiation esophagitis
Reflux esophagitis