Heartburn is one of the causes of asthma and chronic cough.

Though it is called "heartburn", the actual problem has nothing to do with the heart. It is simply called heartburn because of the breastbone is where the pain begins. Some other heart problems share the same symptoms with heartburn.

At any given moment, there is plenty of acid in the stomach. Sometimes, this acid can move upward and the lower esophagus will get a good dose of it. This acidic exposure of the lower esophagus is experienced as heartburn. The lower esophageal sphincter (LES) that separates the esophagus from the stomach is normally meant to contract in order to keep the acid away. Sometimes (for example during swallowing) the sphincter has to relax and at such times it is possible for acidic stomach contents to reenter the esophagus. This return is referred to as reflux. The rhythmic muscular contractions in the esophagus (called peristalsis), move the food down past the LES.

There are no tests for the direct determination of gastroesophageal reflux disease (GERD). So all the doctors can do is study the symptoms to figure out its presence. In case the study of symptoms does not yield conclusive results then the only option left is to conduct tests to rule out other possible symptomatic factors.

Some of the tests are:

pH monitoring. In this case, a probe is placed through the nose into the esophagus to record acid levels. Reflux effects are always taking place in small, inconsequential amounts in the lower esophagus. That is why it becomes necessary to record the acid levels over a long period. A minimum of 24 hours is considered average.

Another way is to take x-rays of the upper digestive tract soon after consuming a solution containing barium. This can help with determining the reflux of barium in the esophagus, another suggestive factor for the presence of GERD.

Manometry is a test in which a pressure sensor called the monometer is passed into the esophagus via the mouth in order to measure the pressure of the lower esophageal sphincter.

Endoscopy involves the direct visual examination using a video camera that is lower through the mouth into the esophagus and stomach. This is a good way of looking for esophageal inflammation.

In Biopsy, a tissue sample is taken from the esophagus and studied for inflammation, cancer, and other problems.