Acid reflux occurs when stomach contents, including acid, flow backward into the esophagus. This happens because the lower esophageal sphincter (LES), a muscular valve, relaxes when it should remain closed, allowing acidic contents to ascend. While occasional reflux (heartburn) is normal, persistent reflux is diagnosed as Gastroesophageal Reflux Disease (GERD). Ignoring chronic GERD allows stomach acid to repeatedly damage the delicate lining of the esophagus, leading to a progression of physical consequences.
Immediate Damage: Esophagitis and Ulceration
Untreated acid reflux leads to esophagitis, the inflammation and irritation of the esophageal lining. The esophagus lacks the protective mucus layer found in the stomach, making it vulnerable to stomach acid. Chronic exposure causes the tissue to swell and become red and raw, a condition known as erosive esophagitis.
If inflammation persists, the constant chemical burn can wear away the protective surface layers, forming open sores called esophageal ulcers. Ulcers can cause significant pain, difficulty swallowing, and potential bleeding. The presence of these ulcers indicates substantial tissue destruction that requires medical intervention.
Structural Complications: Esophageal Strictures
The body attempts to repair damage caused by chronic esophagitis and ulceration. This cycle of injury and repair results in the formation of scar tissue, a fibrous material less flexible than the original esophageal lining. Over time, the accumulation of this dense scar tissue causes the esophagus to narrow, creating an esophageal stricture.
This physical narrowing interferes with the primary function of transporting food to the stomach. The most common symptom is dysphagia, or difficulty swallowing, as solid food may get stuck. In severe cases, the stricture can prevent both food and liquids from passing, requiring an emergency procedure to widen the opening.
The Most Serious Risk: Barrett’s Esophagus and Cancer
Long-term, unchecked acid exposure can lead to Barrett’s Esophagus (BE). This condition replaces the normal squamous cells lining the esophagus with columnar cells, resembling the lining of the small intestine. This cellular transformation is a protective response to chronic injury, but it fundamentally alters the tissue and is the only known precursor to Esophageal Adenocarcinoma (EAC).
The progression involves dysplasia, where the cells become increasingly abnormal in appearance and organization. Dysplasia is classified as low-grade or high-grade, with high-grade representing a late-stage precancerous change. While the annual risk of progression to EAC is low for non-dysplastic BE (0.12% to 0.40%), the risk increases substantially for those with low-grade dysplasia. Individuals diagnosed with BE require regular endoscopic surveillance to monitor cellular changes and detect cancer at the earliest stage.
Extra-Esophageal Complications
The damage caused by untreated GERD is not limited to the esophagus; refluxate traveling higher up the throat can affect structures outside the digestive tract. The respiratory system is frequently affected when small amounts of stomach acid or digestive enzymes can be inhaled, a process called micro-aspiration. This causes irritation to the airways, leading to chronic cough, persistent hoarseness, and laryngitis, which is the inflammation of the voice box.
For individuals who already have respiratory conditions, such as asthma, the aspiration of reflux material can exacerbate their symptoms, making breathing more difficult and increasing the frequency of attacks. Another common consequence that occurs entirely outside the esophagus is dental erosion, resulting from stomach acid reaching the mouth. The highly acidic nature of the refluxate slowly dissolves the enamel on the teeth, typically on the inner surfaces, leading to increased sensitivity and decay.