Heartburn
Nerve fibers in the esophagus get stimulated when there is a backward movement of acid from the stomach to the esophagus, popularly known as acid reflux. The most common result of this phenomenon is heartburn, a pain that most patients of GERD have experienced. It is like a burning in the center of the chest, behind the sternum. Some patients experience the pain as a sort of sharp pressure rather than a burning sensation. It is somewhat like heart pain, or angina. While in some patients it starts high in the abdomen, extending up to the neck, others complain of pain extending up to the back. Heartburn is more often than not, experienced after meals, as that is the time when reflux peaks. Also, it is felt more when the individual is in a prostrate position, as then the effect of gravity is not working to help push the food down into the stomach. Acid is returned to the stomach more slowly and therefore, reflux occurs more easily.

Heartburn is felt sporadically by patients of GERD. Sometimes, for a period of several months, episodes may be very frequent and subsequently reduce or even disappear for a while. But heartburn is a problem that almost always recurs and has to be lived with for a lifetime.

Regurgitation
When refluxed liquid appears in the mouth, it is known as regurgitation. Even in patients of GERD, only small amounts of liquid reaches the upper portion of the esophagus, most of it remaining in the lower esophagus. Sometimes, however, greater amounts of liquid (often even food) are refluxed and reach the upper esophagus. Some individuals in particular, experience this often, but others do not.

The upper esophageal sphincter (UES) is situated at the upper end of the esophagus. It performs much the same action as the lower esophageal sphincter (LES) with respect to the throat. That is, it keeps the contents of the upper esophagus from finding their way back into the throat. Occasionally, when small quantities go back up into the throat, an acid taste is felt in the mouth. The acid in this regurgitated liquid can erode the teeth over prolonged periods of time.

Nausea
Some patients, though not many, report moderate to acute nausea and vomiting. It is as yet unclear why certain patients complain of mainly nausea while others complain mainly of heartburn.