Why is nausea such a common symptom of illness?

ISTM that nausea can be a symptom or side effect of just about anything. What is it about the stomach that is such a harbinger of illness as opposed to the lungs, spleen or left big toe? What is the physical mechanism that causes nausea? Do I have nerves running from my stomach to my brain whose sole purpose is to make me feel lime throwing up?

(Yes I have been sick today)

Anything that triggers the parasympathetic nervous system will tend to cause nausea. Part of the reason is that parasympathetic stimulation tends to cause gastropareisis, or paralysis of the stomach. When it just sits there, with all its contents sloshing around, vomiting is often not far behind.

Infections, fevers, sudden releases of cellular immune modulators into the bloodstream, abnormal sensory input (like dizziness, visual changes), all tend to trigger parasympathetic activity, as does stress and sudden pain.

One hypothesis says the body is wired this way because ingestion of toxins may be responsible for any sudden change in body status; so the body is wired to stop eating, and even purge the stomach contents when system dysfunction arises, as to cease ingesting/expel said toxin. (Said explanation smacks a bit too much of creationism for my taste, but it is an interesting discussion point.)

More could be said on this topic, but not by me at this moment, as I’m feeling just a little queasy.

I don’t know, sounds perfectly reasonable to me. Most of the time, when you’re nauseous, it is because you ate something you shouldn’t have (which was probably even more true, back before modern food preservation). And people who react to such substances by throwing them up would tend to be more successful than people who don’t react that way, so evolution goes to work on it.

I just wanted to say that this is a very good question. It is an obvious fact yet not many people recognize it as a fact. Nothing really to contribute here but, Nars Ginley, have you considered the medical field as simple questions like this can make a difference…

Thanks Hennessy but at the age of 48 I’m a bit old to be changing careers (I’m a computer programmer). BTW, my dad taught biochemistry in medical school and my son is interested in becoming a doctor. I guess this sort of thing is in our Gene’s. (A little pun that no one gets but me. My dad’s name is Gene.)

Since I was 4 years old, 90% of the time when I have nausea it’s from a migraine (and in the past 10 years, sometimes my period - or both at the same time, yay!). I’ve always wondered why the hell nausea and vomiting have to be a side-effect of my headaches… I suppose my parasypathetic nervous system is just being triggered. It is a brain dysfunction after all.

To be sure, other things cause nausea and vomiting that don’t rely so much on parasympathetic stimulation. So this one mechanism is not the reason for all such episodes.

In addition to getting nausea via the parasympathic and stomach, as Qadgop explained, anything that affects the head, whether migraines or fever or bacteria/ virus toxins, can affect the motion sensors in the inner ear, which can then also cause nausea.

Qadgop the Mercotan - “creationism”? why?

After seeing him about it many times, my doctor has come to the tentative conclusion that my frequent nausea is caused by Irritable Bowel Syndrome. When I stop eating the food triggers I’ve figured out, it pretty much goes away, so I think he’s onto something.

Funnily enough, I never vomit.

Because it’s the sort of reasoning that’s after the fact and implying that nature (or evolution) “fixed” a problem with some sort of rational plan. Evolution doesn’t “think” or “plan” or even “wire” an organism in any way, because it’s not an active force. Anthropomorphizing evolution - saying that “the body is wired this way” - is soft creationism.

I could WAG an opposite argument that animals that don’t get nauseous from rotted food would survive to reproduce better, because they wouldn’t be losing the calories from the food, and they wouldn’t risk sodium and potassium imbalance and metabolic alkalosis from loss of stomach acid. If they survive the bacterial assault, they’d be more fit to reproduce than their peers who wasted all that energy and bodily fluids by throwing up. If this “not-nausea” trait can be passed on genetically, perhaps in the future housecats won’t stain carpets so much. :smiley:

Since evolution is never over, and it’s not a thinking process, any “why” answer to the evolutionary adaptation question is moot. Good for discussion, but we’ll never know for sure, because the end of the story hasn’t been written yet.

Exactly! :slight_smile:

I also like this. We should do an inverse WAG whenever someone comes up with yet another evolutionary science-based “just so story” Not that that will actually stop the questions. But still, funny.

I know, right? I first saw this technique in a thread here, I believe. There was another “why does yummy food make us fat?” thread in which someone brought out the idea that putting on fat readily is “evolution’s way” of protecting us through famine. Or, put more scientifically, that proto-humans with a gene mutation which made them put on more fat were able to reproduce at greater rates and pass on the “fat gene” to their offspring, and so most of us now have the propensity to put on weight whenever possible.

Which sounds good, and in fact I quite believe is likely to be the case, but someone else brought up the “inverse WAG” (I love that term!) that fat asses can’t outrun saber toothed tigers, nor run down tasty wildebeast for food, and actually it was/is skinny genes which held the evolutionary advantage for humans. We fatties aren’t fat because of our evolutionary advantage, but despite it.

And really, at the end of the day, who knows? It’s fun to speculate, though.

I really hate skinny genes. Worst fad ever (she says while eating burritos that will go straight to her ass… ).

There is a world of difference between creationism and unverified (and even unverifiable) speculation about evolutionary mechanisms.

It’s almost always unverifiable. Creationism is purely about a decisions made before the fact, and evolution is totally about random events.

I know there are plenty of evolutionists who believe that evolution is based on the result of every possible permutation of genetic structures, but that wouldn’t be possible in the time frame involved. We are all the remnants of chance interactions between genetics and environment. ‘Fitness’ is a factor only based on the random occurence of ‘fitter’ genetics and environment among the finite random permutations that actually occured.

I wonder what age has to do with it if anything?

I remember throwing up as a kid whenver I got the flu. Same thing with my three daughters.

However, as an adult, flu is limited to aches and pains for me.

IANAD. This seems logical to me. Also, two other symptoms of illness, diarrhea and a runny nose, also help expel potential poisons.

On so many of the drug specs (required by FDA) nausea is listed as one of the adverse reactions, in a greater or lesser percentage of people.
I was recently titrated off Lithium, and for nearly two weeks I was vomiting in a bucket. How cum? Shrink was all mumbo jumbo about it.