The majority of people suffer from acid reflux. This disease is also known as gastroesophageal reflux disease, GERD for short. It is a common condition when stomach acid and parts of stomach contents come back in the mouth. You should not confuse reflux disease and heartburn which is a common mistake. The acid does not flow into the mouth. The main reason for acid reflux is improper work of the lower sphincter in esophagus. The other causes of this disease are hot and acidic food , hiatal hernia, yeast infection, peptic ulcers, alcohol and smoking.