In hypochlorhydria and achlorhydria, there is low or no gastric acid in the stomach, potentially leading to problems as the disinfectant properties of the gastric lumen are decreased.  In such conditions, there is greater risk of infections of the digestive tract (such as infection with Vibrio or Helicobacter bacteria).
In Zollinger–Ellison syndrome and hypercalcemia, there are increased gastrin levels, leading to excess gastric acid production, which can cause gastric ulcers.
In diseases featuring excess vomiting, patients develop hypochloremic metabolic alkalosis (decreased blood acidity by H and chlorine depletion).
Gastroesophageal reflux disease occurs when stomach acid repeatedly flows back into the Esophagus, this backwash (acid reflux) can irritate the lining of the esophagus.
Many people experience acid reflux from time to time. However, when acid reflux happens repeatedly over time, it can cause .
Most people are able to manage the discomfort of  with lifestyle changes and medications. While it is uncommon, some may need surgery to ease symptoms.