Acid reflux is the flow of the acids in a backward direction from the stomach to the esophagus. These acids are primarily used in the digestion of food which a person consumes. The walls of the stomach are quite strong and do not get effected by these acids in an adverse way, but when these acids start to flow in the esophagus, lungs etc, they can cause asthma, chest pain, dental erosion, hoarseness in voice, regurgitation and dysphagia.
Though the exact cause of the acid reflux is not yet known, researches have provided some leads. The main cause is said to be the malfunctioning of the lower esophageal sphincter that divides the esophagus from the stomach. The sphincter stops working at an appropriate time which results in the blockage of the entry of the acids into the esophageal tune. A severe heartburn can occur right between the chests which is the evidence of the flow of the acid in a backward direction in the human body.