Gross question of the day: how is diarrhea a side effect of dehydration?

rad65

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This is a question that has plagued me for years. It's known that diarrhea/watery stool is a side effect of being dehydrated, which is extremely counterintuitive to me. I understand that your body functions poorly when dehydrated and that causes your large intestines to not filter water out as efficiently, but doesn't that make the human body seem kind of dumb, or at least fatalistic as it basiclly increases the pace of your demise if you're legitimately trapped and dehydrated? We have evolved over millions of years (or 6,000 depending on what you believe), so why wouldn't our bodies have adapted to conserving water when we are in a position of lacking hydration? If anything, stools should be harder when you are dehydrated as every last drop of water is squeezed out by your large intestine. I know this line of thought is gross, but I have honestly wondered this off and on for at least five years.
 

carolina

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Shouldn't your question be dehydration a side effect of diarrhea?

Diarrhea is not a side effect of dehydration IMHO.... IMHO it is the reverse... Diarrhea causes water loss, which causes dehydration....
 

strange_wings

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Not all dehydration is caused by diarrhea. To assume so is ignorant. Improper fluid intake, dieretics, low blood volume, and sweating+ heat are common causes.

It becomes a side effect when rehydration is too rapid and there isn't a proper electrolyte balance.

Heat exhaustion can cause diarrhea and vomiting, too. Though you'd think the body wouldn't want to make dehydration worse in that state, the stress it's under doesn't make it behave in what we would think of as logical.
 
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rad65

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Originally Posted by Carolina

Shouldn't your question be dehydration a side effect of diarrhea?

Diarrhea is not a side effect of dehydration IMHO.... IMHO it is the reverse... Diarrhea causes water loss, which causes dehydration....
That's my whole point. That is not how it is. Sure, you can get dehydrated from diarrhea, bu I'm talking about when you are already dehydrated, your body responds with diarrhea. Ask any runner who has forgotten to hydrate before a long run over summer, it's definitely the dehydration that happens first.
 
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