What is the cause of hiccups?

Diaphragm irritation: You can be reassured that they happen to almost everyone at some point, the most common cause is thought to be diaphragmatic irritation. Occasionally they can be very persistent and require medical treatment.

Irritation: The hiccups are contractions of the diaphragm, the muscle that separates the abdomen from the chest and responsible for breathing. These contractions are produced when the phrenic nerve is irritated.

Muscle spasm: Hiccups are involuntary, spasmodic contractions of the diaphragm (muscle separating thorax from abdomen) and the muscles between the ribs. Hiccup bouts are caused by distention of the stomach from overeating, carbonated beverages, aerophagia (swallowing air while chewing). Other causes include sudden changes in GI temperature and alcohol ingestion.