Heartburn is an all-too-familiar burning sensation in your chest, throat and stomach. Sometimes called "acid indigestion," it occurs when stomach acid comes up from the stomach and into the throat. Regularly-occurring heartburn can also be a sign of a more serious condition like GERD, which is the chronic reflux of stomach acid into the esophagus. Two symptoms that indicate you could have GERD include persistent heartburn (two or more times per week) and difficulty swallowing (due to acid irritation that has caused the esophagus to become inflamed). Left untreated, chronic heartburn and GERD can lead to esophagitis, ulcers, or strictures (narrowing of the esophagus) and can increase the risk of esophageal cancer.