Hiccup is usually a minor nuisance but prolonged hiccups can be a major problem.

Hiccup is a sudden, involuntary contraction of the diaphragm - the main breathing muscle under the lungs. This sucks air rapidly into the lungs, snapping shut a valve (the glottis) above the voice box (larynx). This snapping makes the characteristic sound of a hiccup.

Hiccups start suddenly, usually happen from 4 to 60 times a minute, and usually last for only a few minutes.

Hiccup may occur after stretching of the stomach following rapid eating, drinking, or swallowing air. Other common causes are: sudden excitement, a rapid change of temperature or drinking very hot or cold drinks.

There are rare causes which are serious:

* Irritation of the diaphragm due to infection, or cancer spread from elsewhere

* Irritation of the phrenic nerve (which controls the diaphragm) by cancer or chest surgery

* Brain infection or tumour

* Severe kidney failure

* Severe general infections

Treatment is needed only for persistent hiccups. Anti-spasmodic and anti-epileptic drugs may help the hiccups, but the underlying cause itself must be treated.

If hiccups are persistent, eating and drinking can be difficult, with risk of inhalation of food or drink. Hiccups can be very tiring to someone who is ill with one of the rare serious causes.