When you eat or drink proton pumps in your stomach release acid which helps break down food and kill bacteria, because the stomach lining is protected this doesn't hurt at all. Usually the valve at the base of the oesophagus keeps the acid in the stomach so you never feel it. Sometimes that valve relaxes and allows acid to escape into the oesophagus, which has no protective lining. When the acid comes into contact with the oesophagus it can become sensitive and you may experience a burning sensation in your chest and throat. This is heartburn, and it can be quite painful. Frequent heartburn is heartburn that occurs twice a week or more the repeated flare-ups of frequent heartburn can disrupt sleep and get in the way of everyday life. Nexium Control is an effective way to treat frequent heartburn.