Ulcerations in the esophagus is caused by chronic reflux disease or by "foreign body." A "pill" lodged in the esophagus dissolves and damage to the mucosa occurs. 
Taking medication with a full glass of water helps prevent medications from lodging in the esophagus. Treatment of esophageal ulcers is the same as for esophagitis.
Esophageal reflux disease with or without ulceration is treated with H2 antagonists medications and antacids. Candida esophagitis is a fungal infection and is treated with antibiotics. Non medical measures to reduce the occurrence of reflux include dietary measures such as:
- Avoiding fried, fatty or spicy foods
- Limiting alcohol and caffeine, smoking
- Avoid eating 2-3 hours prior to bedtime
- Elevating the head of the bed 6-8 inches on blocks
- Losing weight (if necessary) also helps