Esophageal infections occur primarily in patients whose immune system has been compromised severely as, for example, by organ transplantation with the administration of potent immunosuppressive drugs, by acquired immunodeficiency syndrome (AIDS), by chemotherapy, or by advanced malignancy.

Although the esophagus is susceptible to infection by a host of fungi, viruses, bacteria, and parasites, most infectious esophagitis is caused by only three microorganisms: candida, herpes simplex virus (HSV), and cytomegalovirus (CMV). Odynophagia (pain on swallowing) and dysphagia (difficulty with swallowing) are the typical presenting symptoms of infectious esophagitis.

Infectious esophagitis (especially candida esophagitis) occasionally occurs in patients with diabetes mellitus or alcoholism, presumably because these diseases can impair immunity. Antibiotics and corticosteroid therapy both can predispose to candida esophagitis, as can abnormalities that delay the clearance of candida from the esophageal lumen such as progressive systemic sclerosis (scleroderma), achalasia, and esophageal strictures.