The reflux of stomach acid back into your esophagus is called gastroesophageal reflux disease (GERD). Acid reflux can cause irritation of the esophageal lining. Acid reflux is common among many people. Acid reflux with mild symptoms occurs at least twice a week, and moderate to severe symptoms occur at least once a week. Many people can manage the discomfort of GERD by changing their lifestyles and taking over-the-counter medications. However, strong medications may be required for those with severe symptoms.