A hiccup is an involuntary contraction (tightening) of the diaphragm, the sheet of skeletal muscle that lies under the rib cage and helps to control breathing. Normally, when you inhale (breathe in), the diaphragm pulls down, helping to suck air into the lungs. When you breathe out (exhale), the diaphragm relaxes, the lungs are squeezed, causing air to be pushed back out through the nose and mouth. Sometimes, however, the diaphragm becomes irritated. It jerks downwards—often at regular intervals—making you suck air into your throat suddenly. When this incoming air meets your voice box, the vocal cords close, making a “hic” sound.

Causes of hiccups

No one knows quite why hiccups occur. Most cases of hiccups come after eating or drinking too much or too quickly. Some people get them after drinking fizzy drinks or eating spicy food. In rare cases, hiccups can last for a long time. If they last longer than a month they are called "intractable", and are linked with certain medical conditions.

Remedies

It's common to get hiccups now and again, and there is no need for alarm. In most cases, they disappear without treatment within a few minutes. Everyone has their own remedy for stopping them. Simply holding your breath (and counting to 10) often causes them to stop. Breathing into a paper bag increases the amount of carbon dioxide in the lungs, which may relax the diaphragm. Other common suggestions are: biting on a lemon, sipping ice-cold water, tasting vinegar, drinking water from the "wrong" side of the glass, or pulling your knees up to your chest.