context: Gastroesophageal reflux disease ( GERD) can be thought of as chronic symptoms of heartburn. The term refers to the frequent backing up (reflux) of stomach contents (food, acid) into the esophagus -- the tube that connects the throat to the stomach. GERD also refers to the array of medical complications, some serious, that can arise from this reflux. Though it causes discomfort, occasional heartburn is not harmful. About 20% of adults in the U. S. experience symptoms such as heartburn and acid regurgitation at least once a week. But if you have heartburn frequently and it is untreated, your stomach's acid may inflame the lining of your esophagus or swallowing tube, potentially narrowing it. Stomach acid may also change the cells of the lining of your esophagus. This change, called Barrett's esophagus, increases the likelihood of certain cancers of the esophagus. Only a small percentage of people with GERD develop Barrett's esophagus. Your stomach's contents can also move into your throat, irritating your throat or vocals cords and causing hoarseness and a chronic, dry cough. Anyone can develop GERD at any age but you are more likely to develop it as you get older. Pregnant women are especially prone to reflux. GERD can cause a pain in your chest that can be confused with the symptoms of a heart attack. Sometimes medical professionals diagnose GERD after evaluating a patient for episodes of chest pain that are found to be unrelated to heart disease. IMPORTANT! Never ignore pain in your chest. Seek immediate medical help. Call 911. Any delay in getting help may be fatal. If your doctor says you have GERD, ask what you should do when you have chest pain. Esophagitis, or inflammation of the esophagus, is a complication of GERD. If GERD is left untreated, esophagitis can cause bleeding, ulcers, and chronic scarring. This scarring can narrow the esophagus, eventually interfering with your ability to swallow. One major complication which occurs in about 10% to 15% of people with chronic or longstanding GERD is Barrett's esophagus. Barrett's esophagus results when the normal cells of the esophagus are replaced with cells similar to those of the intestine. This increases the risk of esophageal cancer. Developing Barrett's esophagus does not mean you will get cancer, but your chances of getting cancer will be increased. Your doctor will want to check you on a regular basis in order to detect any cancer in its early stages. People who have Barrett's esophagus may require periodic endoscopies with esophagus biopsies to check for pre-cancer cells (dysplasia). GERD can lead to the reflux of fluid into the airways; this can result in choking, coughing, or even pneumonia. In some patients, reflux may worsen asthma symptoms. Treating GERD may help improve asthma symptoms in these people. And GERD can be worsened by asthma and by some of the medicines that are used to treat asthma. GERD can also lead to chronic hoarseness, sleep disturbance, laryngitis, halitosis (bad breath), growths on the vocal cords, a feeling as if there is a lump in your throat, earaches, and dental problems. When you swallow, a muscular valve known as the lower esophageal sphincter, or LES, which is located where the esophagus joins the stomach, opens to let food into your stomach and then closes to keep your stomach contents from coming back up. The major cause of GERD is that this valve does not function the way it should -- either because it is weak or because it relaxes inappropriately. A hiatal hernia (in which a portion of the stomach protrudes above the diaphragm into the chest) and poor esophageal muscle contractions can also contribute to GERD. Diet and lifestyle also play a role. Fatty foods, mints, chocolate, alcohol, coffee, and tea, all relax the LES. So does nicotine from cigarettes or chewing tobacco. Hormonal changes associated with pregnancy can temporarily weaken the LES, too. Obesity can lead to GERD because the pressure of extra weight pushing on your abdomen may "overpower" the LES, allowing reflux to occur. The same mechanism explains reflux that may occur when you bend over at the waist.