What is metoclopramide and what serious side effect limits its use?

Metoclopramide is a prokinetic and antiemetic drug that works by blocking dopamine receptors and enhancing upper gastrointestinal motility. It is used for gastroparesis, nausea, and gastroesophageal reflux disease. The FDA issued a black box warning because long-term use beyond 12 weeks significantly increases the risk of tardive dyskinesia, an often irreversible movement disorder causing involuntary facial and tongue movements. Elderly patients, particularly women, are at highest risk.