Stopping Hiccups with Science

I first got the idea to do this episode through self-reflection. When I was a teenager, my family and I took one of many trips up to Alaska, where my grandfather was a lifelong bush pilot (not counting a couple of interruptions to fly in World War II and to have a career as a 747 captain for American Airlines). On one such trip, he took us out to a rough, rocky landing strip at a fishing lodge in the middle of nowhere. I had a horrible bout of the hiccups that seemingly would not stop. As fortune favors the foolish, it so happened that a very old man was the only other guest of the lodge — it was said that he was an elder of an Athabaskan tribe, which seemed exceptionally impressive and mysterious to the adolescent me. And what's more, he had a cure for the hiccups. He stood behind me and placed his hands on my face, and felt with his index fingers for a small notch at the bottom medial corners of my eye sockets. He found them, and held his fingers there with significant pressure — almost but not quite enough to be painful — for a solid spell, until I had not hiccuped for a full minute. And then he released me, and my hiccups were cured. The ancient wisdom of the tribal elder had done its magic.

I've used this technique on myself countless times ever since, with a success rate that (to my fallible memory) has been faultless. But it was through self-reflection, tempered with over a decade of Skeptoid, that I finally said "Hey, my anecdote does not equal data," and maybe it was time to see what science — unencumbered by personal anecdotes — has to say about cures for the hiccups.

To understand how to stop hiccups, it's first necessary to understand exactly what they are and why they happen. A hiccup consists of two rapid, involuntary muscular actions. The first is a spasm of your diaphragm, the large abdominal muscle right below your lungs. This spasm causes your lungs to suck in a brief gasp of air. Then your glottis reflexively snaps shut to stop more air coming in. These combine to make you involuntarily say "Hic!"

The diaphragm is controlled by the phrenic nerve. This connects to the C3, C4, and C5 spinal nerve roots and goes down through your chest to the diaphragm, where it controls breathing. A quick bioelectrical signal through this nerve is what manifests as a hiccup. Another nerve that's involved is the vagus nerve. This one comes out of your brain stem, winds all over the place, and ends up at your stomach and digestive tract.

Now there are all kinds of things that are known and/or theorized to cause the hiccups. The most dramatic, and unusual, involve injuries to those two nerves; either a tumor, an impingement, or something like that. More common causes involve the digestive system — something you ate or drank — and probably tell the vagus nerve to tell the phrenic nerve to initiate hiccups. These include:

• Eat or drink too quickly.
• Eat or drink too much.
• Drink carbonated beverages.
• Eat or drink something very hot or very cold.

Some cases of the hiccups, usually the long-lasting chronic kind, have deeper and darker causes, including:

• Hernia
• Kidney failure
• Meningitis
• Aneurysm
• Stroke
• Multiple sclerosis
• Brain lesions
• Injury to the vagus nerve

But let's hope you don't have any of those. If you do have hiccups that aren't associated with your digestive system, but somehow your brain decides hiccups are the best course of action anyway, it could be from one of these:

• Stress from fear.
• Stress from over-excitement.
• Stretch your neck in a funny way.
• Inhale certain fumes.
• Certain drugs, including general anesthesia, some chemotherapies, or a class of anxiety drugs called benzodiazepines.

Now, it seems to me — and probably to most quasi-rational people — that hiccuping would do little to rescue your body from any of these latter conditions. So why is the body doing it? In fact, hiccuping doesn't seem to solve anything at all; why did it evolve in us? What good is it?

There are two leading theories of an evolutionary explanation for hiccups. One is that it's left over — way, way over — from the days when our remote ancestors had gills. That was some 450 million years ago, when some brave fish first ventured up onto land, possibly looking for a hamburger. These earliest adventurers had both gills and lungs, and while that's handy, it's also a bit of a management situation. To get water flowing past your gills, you have to suck in rapidly with your lungs; but to prevent water going into your lungs, you have to close off your glottis. In summary, you have to hiccup. Repeatedly. The theory is that this sequence is an evolved behavior that remains vestigial in us, even 450 million years later.

If that time span seems a bit too long for your tastes, then have a look at the other leading theory. It's to do with suckling babies. When a baby suckles, it always gets some amount of air in its stomach, taking up space which could otherwise be taken up by milk. A baby who can burp the air out of its stomach can accommodate up to 25% more milk; and such a baby has an obvious evolutionary advantage over babies that get less nourishment. Having air in the stomach triggers those nerves that serve the digestive system, and triggering hiccups causes the diaphragm to spasm, squeezing the air out of the stomach, and closing the glottis to make sure that air doesn't go into the lungs, but goes out. Hiccups thus aid the process of burping the baby, giving it a nutritional advantage. So perhaps we hiccup as adults because doing so as infants made us incrementally more likely to survive into adulthood.

Whatever the cause or the mechanism, we get the hiccups. We usually don't like them because they're annoying. So when we get them, we like to make them stop.

Easy folk treatments

So let's have a look at some of the ways we've traditionally done this. And traditionally, the most common treatment is to do nothing at all — just put up with the hiccups — and almost all of the time, they soon go away on their own. But if waiting them out isn't your bag, here are some things that many people find to work:

• Breathe into a paper bag, just as you would to treat hyperventilation. It is believed that increasing the amount of carbon dioxide in your lungs may relax the diaphragm to the point that the spasms stop. Holding your breath is another way to accomplish the same thing.
  
  
• Drink some water upside down, by leaning far forward and drinking from the opposite rim of the glass. There are conflicting opinions on why this works. Some think it's merely the contraction of the abdominal muscles from bending over that takes precedence over the hiccup nerve signals; another hypothesis is that the swallowing of the water forces air into the stomach, thus triggering a burp, thus relaxing the vagus nerve.
  
  
• Eat a spoonful of sugar or peanut butter, or something else that's hard to swallow. The idea here is that the difficult swallow distracts the vagus nerve to focus on that, instead of the hiccups.
  
  
• Performing the Valsalva maneuver — a forceful attempt to exhale against a closed airway — and holding it for up to 30 seconds if you can, might do it. This not only engages the abdominal muscles, but also the diaphragm, recovering manual control over it from the hiccup response.
  
  
• A good scare! Scaring someone with the hiccups does work in many cases. The mechanism for this is believed to be, once again, the vagus nerve. It's involved in the fight or flight response, and putting yourself into that mode can distract the vagus nerve from triggering hiccups.

Of course, treatments that depend on distracting the sympathetic nervous system — of which the vagus nerve is a major component — are only likely to be effective against hiccups that are being caused by the vagus nerve. Not all cases are.

Drug interventions

In rare cases, the hiccups just won't go away. If you still have them after a couple of days, you may want to go see a doctor, because there actually are drug treatments that work.

• First, and seemingly most effective, is Baclofen: This drug is a muscle relaxant and antispasmodic, and it cures hiccups with near 100% success with a single dose. Regardless of what's triggering the hiccups, relaxing the diaphragm stops them from happening.
  
  
• Chlorpromazine: This is an antipsychotic often used for anxiety or schizophrenia. The idea is to get your brain to stop deciding hiccups are the right response for whatever signals it's getting from the vagus nerve.
  
  
• Metoclopramide: This is mainly used as a gut motility stimulator, to get things moving down below. If you can evacuate the stomach faster, the idea is that it will tell your vagus nerve that there's nothing wrong in your stomach anymore.

There are plenty of other drugs listed that mainly work in one of these basic mechanisms. But in the rarest of cases, even drug interventions won't do the trick.

Surgical remedies

The next step is that we start to get invasive. Here are two procedures that have been found to work in the worst cases.

• A nerve blocking anesthetic can be injected into the phrenic nerve, preventing it from sending that signal to spasm. This has to be done carefully to prevent you from becoming unable to breathe.
  
  
• A device can be implanted to deliver electrical stimulation to the vagus nerve. This sends electrical impulses to the brain, which is one way to treat certain types of epilepsy; but the same stimulation has also been found to stop hiccups in some patients with the very worst of chronic cases.

One thing I was really hoping to find for this episode was a single huge clinical trial that tested all these many possible treatments against each other to see what works and what doesn't. But, so far as I could tell, no such thing exists. It's hard to recruit test subjects who all have the hiccups. But for all of these, I found citations to smaller studies that focused on a single method or two. As always, you can check the references and further reading suggestions on the bottom of this page.

What I also didn't find is any evidence that hiccups can be cured by having an Athabaskan tribal elder apply pressure to your eye sockets. But if nothing else is working for you, it might be worth a try to put that on your list. Unless, of course, you're one of those skeptics who values evidence over anecdotes.

By Brian Dunning
Follow @BrianDunning