Why do we get hiccups?

A hiccup is a sudden involuntary spasm of the diaphragm, the muscle beneath the lungs that drives breathing. The spasm pulls air in sharply, and almost immediately the vocal cords snap shut — that closure is the “hic”.

The usual triggers are familiar: eating too fast, eating too much, fizzy drinks, an abrupt change of temperature, excitement. All of them irritate the diaphragm or the nerves serving it. Most bouts settle within minutes.

Many of the home remedies share a logic: holding your breath or sipping water slowly nudges up the carbon dioxide in your blood and interrupts the breathing rhythm, which can break the diaphragm’s cycle. They are harmless, though not reliable.

If hiccups run continuously beyond forty-eight hours, or interfere with sleeping or eating, that is a reason to see a doctor — persistent hiccups can point to an underlying cause.

Babies hiccup, and so do foetuses before birth — it is visible on ultrasound. That has led many researchers to think the reflex is evolutionarily very old, and possibly related to learning to coordinate breathing with swallowing.