Under normal conditions, when you eat and drink, the muscle at the bottom of your esophagus closes off so food and liquids will remain in your stomach. This muscle is the lower esophageal sphincter (LES).
However, GERD occurs chiefly because of the following three reasons: The esophagus's normal defenses are overwhelmed by the acid content of the stomach, the contents of the stomach are too acidic, or the food is not cleared from the esophagus fast enough.
When "refluxed" stomach acid touches the lining of the esophagus, it causes a burning sensation in the chest or throat called heartburn. The fluid may even reach the back of the mouth, and this is called acid indigestion. Occasional heartburn is common but does not necessarily mean one has GERD. Heartburn that occurs more than twice a week may be considered GERD, and it can eventually lead to more serious health problems.
For some patients, GERD can cause erosive esophagitis, a condition that causes inflammation, swelling, or irritation of the esophagus. More than half of GERD patients, however, have a non-erosive type of GERD. With the non-erosive form of GERD, referred to as Nonerosive Reflux Disease (NERD), patients experience typical GERD symptoms caused by acid reflux, but they do not have visible esophageal injury.
There is a group of patients who continue to have symptoms of gastroesophageal reflux despite a standard treatment with proton pump inhibitors (PPIs). They have what is known as Refractory Gastroesophageal Reflux Disease (Refractory GERD). Patients who experience refractory GERD usually fall into one of two groups: Those who need more aggressive treatment, and those who have other causes of their reflux symptoms.