The mysterious science of hiccups: why we get them and how to stop them

Pretty much everyone has had a case of the hiccups at one point or another. They're quite common and quite annoying, and your friends likely have different tips about how to make them go away. But is there any scientific data about what works and what doesn't? And why do people hiccup, anyway?

Even scientists are a little bewildered by this. "We still don't know what hiccups do, and our cure for them hasn't improved since Plato," says Robert Provine. He's a neuroscientist at the University of Maryland Baltimore County who studies the evolution of behavior, and he researched hiccuping extensively for his book Curious Behavior: Yawning, Laughing, Hiccupping, and Beyond.

One problem, Provine notes, is that hiccups have been difficult to study: "You can't just go into the lab and ask someone to hiccup for you." That means the research that exists typically concerns people with problematic hiccups that have lasted days, weeks, or years.

But that doesn't mean we know nothing.

1) The world record holder hiccuped for more than 60 years

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Hiccups happen when the diaphragm and external intercostal muscles involuntarily contract, causing someone to rapidly inhale. Then about 35 milliseconds later, the vocal cords slam shut, causing the characteristic "hic" sound. It's a precisely timed series of events.

Doctors also call hiccups singultus or synchronous diaphragmatic flutter.

Having hiccups for an hour or two can be a bother. But hiccups that don't go away can be a sign that there's something seriously wrong with you.

The person generally cited as the world record holder for hiccups is Charles Osborne, an Iowa farmer who had them for 68 straight years — from 1922 to 1990.

Although he was able to have a normal life, some people with intractable hiccups (generally categorized as for more than a month or two) experience insomnia, drastic weight loss, and exhaustion.

And for people with just persistent hiccups (more than 48 hours), it can be a sign of a serious underlying health problem, including nerve damage, a brain tumor, kidney failure, or a reaction caused by various drugs.

So if you've had hiccups for more than two days, it could be time to see a doctor.

2) Some weird potential cures: rectal massage and sex

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Many so-called hiccup cures have existed for quite some time — drinking water, holding your breath, eating sugar, having someone scare you, and on and on. But doctors are still trying new things.

Two publications from 1988 and 1990 describe case studies of a doctor massaging a patient's rectum to cure intractable hiccups. And in 2000, another group reported a case of someone who had hiccups for four days and then was cured after ejaculating during sex.

Both activities stimulate the vagus nerve, which helps control unconscious activity of the heart and digestive tract.

Francis Fesmire, the doctor who published the first rectal massage study, later said that he would recommend sex as a cure instead. "An orgasm results in incredible stimulation of the vagus nerve," he told New Scientist in 2006. "From now on, I will be recommending sex — culminating with orgasm — as the cure-all for intractable hiccups."

3) Increasing carbon dioxide might decrease hiccups

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The few folk remedies that seem to be based on a reasonable scientific concept involve holding your breath or breathing into a paper bag.

At least for patients with intractable hiccups, increasing the concentration of carbon dioxide they breathe has been shown to decrease how often they hiccup.

Holding your breath does something similar: "You’re blocking the motor pattern as well as leading to a buildup of carbon dioxide," Provine says. Breathing into a paper bag would also increase carbon dioxide in the body.

4) The overall evidence on hiccup cures is sorely lacking

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Despite all these intriguing possibilities about how to cure hiccups, the medical literature usually stops with just a case study of one or two patients. And that doesn't really say much.

To know if something actually works, doctors need to perform a controlled medical trial where half the people receive the treatment in question and half receive a placebo for comparison. And hiccups just haven't been a hot area for such trials, which can also be fairly expensive to do.
One recent systematic review of previous medical studies concluded: "We searched for good quality studies that involved adult patients (18 or older) who had experienced hiccups for 48 hours or more. Our conclusion is that there is insufficient evidence to recommend a particular treatment for hiccups."

So if you end up with seriously intractable hiccups that have gone on for a really long time, doctors will pretty much just try a bunch of random things.

They might suction out your stomach or try various drugs. And they'll hope something works. They'll also look for underlying health problems that could be related to this hiccuping annoyance.

Some doctors, when less invasive treatments have failed, have attempted to stimulate the vagus nerve directly with an electrical implant or used an injection of an anesthetic to block the phrenic nerve, which controls the diaphragm. And they've reported a few cases where this has worked.

5) Scientists still aren't sure why we hiccup

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People have floated all kinds of ideas for why hiccuping exists, including some new ones in recent years. However, just because they're newer doesn't mean they're better. Frankly, at this point, they're all conjecture.

One published essay presents the hypothesis that it's an evolutionary holdover from tadpole development. At a certain stage, tadpoles have both gills and lungs, which leads to some interesting breathing gymnastics.

Another is that hiccups are a burp-like reflex that used to help suckling baby mammals get rid of extra air in their stomachs.

And there are many others. Maybe someday someone will fund studies to get to the bottom of this, but it doesn't seem to be high on the list of national priorities.

6) Fetuses get hiccups a lot

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Ultrasounds have detected hiccups in fetuses as young as 8 weeks old, and it's one of the most common behaviors in the womb. At some points, a fetus is likely to hiccup every day, according to Provine.

Newborns also hiccup a fair amount, and the behavior then decreases with age.

This pattern suggests that hiccuping might have some sort of beneficial role in early development, but there's no solid evidence as to what. For all we know, it might not.

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