A hiccup (hiccough) is a spasmodic contraction of the diaphragm that typically repeats several times per minute. In medicine, it is referred to as synchronous diaphramatic flutter (SDF).

For hiccups lasting longer than 48 hours, the following may be done: blood tests, chest x-ray, ear exam, and fluoroscopy.

One technique is to increase carbon dioxide levels in the blood, which may reduce the sensitivity of the vagus nerve in the brain. That nerve, one of the longest in the body, sends signals to many muscle groups, including those in the diaphragm. One can increase carbon dioxide levels by holding one's breath, by rebreathing the air exhaled into a paper bag for a few minutes, or by slowly sipping a glass of water without pausing to take a breath.

Symptoms of hiccups are contraction of diaphragm and a constant “hic “sound from the throat.

The cause of hiccups in children and infants is rarely found. Brief episodes in adults generally are benign and self-limiting. Typical causes include gastric distention (food, alcohol, air), sudden changes in ambient or gastric temperature, and excessive use of alcohol and/or tobacco. Psychogenic causes (excitement, stress) also may result to hiccups. Persistent or intractable episodes are more probable to result from serious pathophysiological processes affecting a component of the hiccup reflex mechanism. More than 100 causes have been described; however, in many cases, the cause remains unknown.