A barium swallow is a radiographic examination that involves the ingestion of a barium-containing contrast agent to visualise the upper gastrointestinal tract, including the oesophagus, stomach, and duodenum, under X-ray imaging. This procedure is crucial for diagnosing conditions such as strictures, tumours, or gastroesophageal reflux disease, as it allows for detailed assessment of structural and functional abnormalities. A key complication can include aspiration pneumonia if the barium is inadvertently inhaled.