GERD results when the lower esophageal sphincter (LES) muscle becomes weakened. The LES sits at the juncture between the esophagus and the stomach and prevents food and stomach liquids from flowing back up into the esophagus.

Weakening of the LES can be caused by the following factors and conditions:

  • Hiatal hernia : When the stomach and the LES protrude into the chest through the opening in the diaphragm normally occupied by the esophagus
  • Surgical destruction of the LES
  • Neurologic disorders or complications (from diabetes, for example) affecting the LES
  • Scleroderma : A disorder that affects esophageal motility
  • Congenital defects of the gastrointestinal or respiratory tracts
  • Certain medications, such as:
    • Bronchodilators
    • Calcium channel blockers
    • Aminophylline
    • Nitrates
    • Sildenafil (Viagra)

Other factors that contribute to LES weakening include the following:

  • Smoking
  • Caffeinated beverages
  • Alcohol
  • Fatty foods, especially chocolate and fried foods

Once the LES is weakened, other factors, such as an increase in pressure in the abdomen relative to the chest, can increase the risk of reflux. See Risk Factors for further details.