Acid Reflux or Gastroesophageal reflux disease (GERD) is a condition in which the liquid content of the stomach backs up or refluxes into the esophagus. The liquid can inflame and damage the lining of the esophagus. This regurgitated liquid mainly contains acid and pepsin, both being produced by the stomach. It may also contain bile. Amongst all the contents of the liquid, acid is the most harmful.

Once GERD starts, it stays for life-long. GERD is a chronic condition and the treatment has to continue indefinitely. The reflux of the stomachs liquid contents into the esophagus occurs in normal individuals also. The difference of it occurring in GERD patients is that the refluxed liquid contains more acid that often remains in the esophagus for longer duration. The body has ways of protecting itself from the effects of reflux and acid. Saliva contains bicarbonate that neutralizes the small amount of acid that remains in the esophagus. Gravity, swallowing and saliva are the protective mechanisms for the esophagus when an individual is in the upright position.

There are various complications arising because of acid reflux.
Ulcers The cells lining the esophagus are sometimes damaged due to the reflux of liquid from the stomach into the esophagus. An ulcer is a break in the lining of the esophagus that occurs in an area of inflammation. It may give rise to bleeding in the esophagus. When the bleeding becomes severe, blood transfusion is required along with endoscopic or surgical treatment.
Strictures Scars are formed when the ulcers of the esophagus heal. The scar tissue shrinks and narrows the lumen of the esophagus. This scarred narrowing is called a stricture. It may cause swallowed food to get stuck in the esophagus.
Barretts esophagus Severe GERD or Long-standing cause cells to change that line the esophagus. These cells then become pre-cancerous and then finally cancerous.
Cough and Asthma Some nerves in the esophagus are stimulated by the refluxed acid, which results in pain. Other nerves that are also stimulated provoke coughing. The stimulated esophageal nerves that connect to the nerves going to the lungs causes the breathing tubes to narrow, resulting in an attack of asthma.
Inflammation of the throat and larynx When the refluxed liquid gets past the upper esophageal sphincter, it enters the throat and the voice box, causing inflammation and soar throat.
Inflammation and infection of the lungs The reflux of liquid into the lungs results in coughing and choking. This can lead to infection of the lungs and result in pneumonia.
Fluid in the sinuses and middle ear Found in children, it is caused when the sinuses and middle ears are closed off from the nasal passages by the swelling of the adenoids. Fluid is then accumulated within them.

GERD is treated with life-style changes, antacids, histamine antagonists (H2 blockers), proton pump inhibitors (PPIs), pro-motility drugs, foam barriers, surgery, and endoscopy.