Cimetidine is a medication primarily used to treat conditions related to excess stomach acid, such as peptic ulcers and gastroesophageal reflux disease (GERD). It belongs to a class of drugs known as H2 blockers, which work by reducing the amount of acid produced by the stomach. Cimetidine is available in both prescription and over-the-counter forms. It can help relieve symptoms like heartburn and indigestion, promoting healing of the stomach lining. However, it may interact with other medications, so it's important to consult a healthcare provider before use.