There are any number of causes for GERD, including eating certain foods that trigger heartburn (chocolate, peppermint, garlic, tomatoes, citrus fruits, etc.); ingesting alcohol and caffeine; eating too much; being overweight; and lying down after a meal.
Certain medications (antidepressants, beta blockers) and some medical conditions (esophageal varices and strictures) also may cause GERD. Usually stomach acid is confined to the stomach. But in some cases when a small valve called the lower esophageal sphincter (LES) malfunctions, it allows acid to seep back up into the esophagus. Reflux disease also is more common in patients with hiatal hernia, in which a portion of the stomach protrudes up into the esophagus.