Why does some gas make you feel sick to your stomach?

April 23, 2021 3:24 PM

AskMe, it's come to this on a Friday night in late-stage pandemic parenting. My family and I are wondering why some gas (read: flatulence, farts) makes you feel sick to your stomach. Sick like nauseous, queasy, like you ate something bad.

And then as soon as you fart, that feeling is gone! We're not talking about the physical pain of gas pressing on your insides like bloating, or sharp or dull pains in your side.

We've got theories:
+ There's "good" and "bad" gas. The components in some gas (the bad kind) make not just gas, but somehow they also make you feel sick.
+ Sometimes gas flows backwards into your stomach and makes you feel sick no matter what's in that specific batch of gas
+ A kind of "nausea bacteria" in your intestine is airborne and some of this bacteria permeates the intestine making you feel gross until it's pushed out
+ Your rectum can sense both mechanical pain (like pressure) and also chemical pain like feeling nauseous, so it's not really your stomach that's nauseous it's your rectum.

But what is it?! We want to know and we want details!

posted by cocoagirl to Science & Nature (9 answers total)

I’ve never felt the way you’re describing? I’ve had stomach pain from gas before- almost like a cramp but never nausea from needs to fart
posted by raccoon409 at 3:40 PM on April 23, 2021 [4 favorites]

Sounds like the symptoms of vagus nerve activation, so closest to your last theory. If different episodes of gas either trigger or don't trigger nausea, perhaps it's the result of the gas being generated or entrapped in different places down the line.
posted by fountainofdoubt at 4:02 PM on April 23, 2021 [5 favorites]

Sensations like nausea get triggered by a combination of external things (smells), body sense (stomach pressure from overeating activates the vagus nerve), and past experiences. This is why people can become nauseous from just thinking about something disgusting, that activates the same part of your brain as something actually disgusting. I have a lot of weird stomach sensory issues so have felt this before, and I don't think there's one cause. It's very difficult for your body/brain to work out when there's an actual physical problem down there and sometimes it guesses wrong. I haven't really found much formal scientific description of the processes involved because it's kind of understudied
posted by JZig at 4:07 PM on April 23, 2021

I have a hard time understanding what phenomena you're describing, you've ruled out all of the feelings I would normally associate with gas.
posted by GoblinHoney at 5:04 PM on April 23, 2021

I've had this a few times recently as I've gotten old enough or had the right prescription combination to cause, uh, extended bathroom events, and they seem to go together about 1/3 of the time. I figured it was gas combined with other digested material to press on something unknown. However, in my estimation it's pressure happening somewhere in the middle of the journey, not at the exit door.
posted by rhizome at 5:30 PM on April 23, 2021 [3 favorites]

I've always assumed it to be a vasovagal thing, some combo of farts and poops and digested food sitting in a way that stretches or puts pressure on the wrong nerves. (I personally have also felt this way when in early labor and when when menstruating, while not feeling in particular pain but with major queasy sweats. So there may be some spots in your body where cramps can happen, that your body doesn't interpret as ouch-pain but with a slightly different this-is-bad-we-should-lay-down-now message. I've also felt this way a lot less since I started taking lactase pills when I eat dairy; turns out that maybe I wasn't a nervous kid, just one with mild lactose intolerance. YMMV.)
posted by tchemgrrl at 5:59 PM on April 23, 2021 [2 favorites]

Without actually knowing the answer, I'd recommend looking into hydrogen sulfide production as part of digestion (and the causes of its production) and the physiological effects of being exposed to it.
posted by porpoise at 12:16 AM on April 24, 2021

I call it gacid. All the pressure aggravates your stomach and may even cause GERD.
posted by serena15221 at 7:20 PM on April 24, 2021 [1 favorite]

I get this sometimes, and I've always put it down to my body being very quick to decide that throwing up is an option (I threw up once from the pain of stubbing my toe). The answers above about pressure on the wrong nerves being responsible for the gas-related nausea are probably correct. But I think it's also as JZig says - our bodies aren't always great at determining the cause of a problem so they try everything to get you to pay attention.
posted by harriet vane at 7:56 AM on April 26, 2021