What Happens Inside You When You Hiccup, and What Is It For?

A Hiccup Is a Sudden Breath In That the Throat Cuts Off

Two things happen, one right after the other. First, the diaphragm, the sheet of muscle under your lungs, pulls down suddenly between breaths, and you quickly suck in air. Second, the glottis, the space between your vocal cords, suddenly closes to stop more air from coming in [2]. The closing is what makes the sound. The word “hiccup” is onomatopoeic: it imitates the noise made when the vocal cords snap shut [1].

The gap between the two steps is tiny. A 2012 paper describes the vocal cords closing about 35 milliseconds after the forceful contraction of the breathing muscles [1]. That is 0.035 of a second, roughly one thirtieth. The breath is barely started when it is blocked, which is why a hiccup sounds like a short, sharp catch and not like a gasp.

This repeats. The same paper says hiccups usually come at 4 to 60 per minute [1].

Signals From the Stomach and Diaphragm Set It Off, and You Cannot Order It to Stop

A hiccup is a reflex, so it does not wait for you to decide. The NHS describes hiccups as involuntary contractions [3]. The 2012 paper says the signals that feed the reflex come from the lower part of the food pipe, the stomach and the underside of the diaphragm, and travel along nerves including the phrenic nerve and the vagus nerve [1].

Everyday triggers fit that picture. Cleveland Clinic lists eating too much or too fast and drinking carbonated drinks [2]. The NHS adds that some people find stress, strong emotions such as excitement, and eating and drinking set theirs off [3]. A trigger does not guarantee a hiccup, and none of the sources here names a single cause for ordinary hiccups.

Babies Hiccup Before They Are Born, and Newborns Do It the Most

Hiccup-like movements can be felt by pregnant mothers and seen on ultrasound in the fetus, before the swallowing and breathing reflexes appear [1]. After birth the reflex is most common in newborns, who spend as much as 2.5 percent of their time hiccupping [1].

Cleveland Clinic calls hiccups in babies common and normal. Its page says the exact cause is unclear, and that providers believe extra gas in the stomach irritates the diaphragm [2]. Those facts make the reflex look old and built in, which makes the next question harder.

Nobody Has Shown What Hiccups Are For, and There Are Two Ideas

The author of the 2012 paper writes that there is no known physiologic advantage for the common hiccup [1]. Two explanations have been put forward, and both are hypotheses.

The older idea is that the hiccup is an evolutionary leftover from gill breathing in animals that came before us [1]. The newer idea, which is the one the 2012 paper proposes, is that hiccups help young suckling mammals get swallowed air out of the stomach, a sort of built-in burp. The paper says hiccups are triggered by air in the stomach, and it ends by admitting there is, as yet, no proof for this hypothesis [1].

So the honest answer to the title is in two parts. What happens inside you is well described. What it is for is still a guess.

No Hiccup Cure Has Been Found, so Home Tricks Are Only Tries

Everyone has a favorite remedy. Cleveland Clinic says experts haven’t found a hiccup cure, although anecdotal reports suggest holding your breath or sipping cold water may help [2]. The NHS lists sipping ice-cold water, swallowing sugar and tasting lemon or vinegar, and says there is no evidence that they work for everyone [3]. A health guide published through PeaceHealth suggests holding your breath and counting slowly to 10 [4].

The pattern across the sources is consistent: these are things people try, not treatments shown to work. Ordinary hiccups usually stop by themselves. The NHS says they should only last a few minutes [3].

If Hiccups Last More Than Two Days, Tell a Grown-Up and See a Doctor

Doctors sort hiccups by how long they last. Cleveland Clinic gives transient hiccups as lasting seconds or minutes, persistent ones as lasting longer than 48 hours for up to a month, and intractable ones as lasting more than a month [2]. The NHS advises seeing a GP, the family doctor in the UK, if hiccups last longer than 48 hours or come back so often that they affect daily life [3]. The PeaceHealth guide says a bout that long can be a sign of a more serious health problem [4].

If you are a child reading this, the rule is simple: if hiccups go on for a couple of days, say so to a parent or another adult you trust.

Try It Yourself: Feel One Normal Breath, Then Count Your Next Hiccups

You need only your hands and a clock or phone timer. Do not try to make yourself hiccup, and do not hold your throat shut on purpose.

1. Sit comfortably and rest one hand on your chest and one on your belly.
2. Breathe normally for a few breaths and notice which hand moves when you breathe in.
3. Next time a hiccup comes on its own, picture the order: a sudden breath in, then the throat closing and the “hic.”

For a longer project, keep a hiccup diary. Write down what you had just done, such as eating quickly, laughing or drinking something carbonated, and how long the bout lasted. After a little while, look back and see whether your own pattern fits the triggers above.

Sources

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