Water filter: How long will it take to fill up again?
March 14, 2008 11:53 PM   Subscribe

How long does rehydration take?

So I spent a lovely time at the ER because my resting pulse rate was nearly double my normal rate. Turns out I stupidly let myself get dehydrated for several stupid reasons. I know! Stupid!

One bag of IV juice knocked the pulse rate down by 20 points and they turned me loose.

It got wondering, during one of several hundred trips to the restroom today, how long would it take to completely rehydrate after being that depleted?

OK, so nobody has enough data to say for sure but are we talking hours or days or...? Just looking for some kind of ballpark scale. Assume no special exertion or hot weather, etc., during the rehydration period.

Also, any special rehydration tips are welcome.
posted by trinity8-director to Health & Fitness (17 answers total)
Well, I've never been insanely dehydrated in that way, but I have been insanely drunk/hungover, which is similar. (The symptoms of a hangover are the same as dehydration, because they are the same thing. Alcohol dehydrates.)

Just drink lots of water, or things with electrolytes in them. Gatorade, VitaminWater, etc. If you have to pee, pee. If you're peeing clear, or pale-lemonade colored, you're safely hydrated.
posted by SansPoint at 12:32 AM on March 15, 2008

Pedialyte - like Gatorade but: cheaper and unflavored. It's usually in the kids/infants section of the pharmacy.
posted by zippy at 12:42 AM on March 15, 2008

Paraphrasing Cody Lundin:

The trick to maximal hydration in the shortest amount of time is to blow water past your stomach and small intestine and into the large intestine where it's absorbed. Drinking an adequate volume of water coerces the stomach into shooting it past the opening between your stomach and small intestine, called the pyloric sphincter. At the start of my field courses, I have students drink at least a quart or two before venturing into the bush. I have them drink to the point of feeling slightly nauseous.
posted by Rich Smorgasbord at 1:31 AM on March 15, 2008

SansPoint: Huh - I didn't realize the two were the same. Interesting.

Water is good; if you become dehydrated, you probably want something with electrolytes in it like Sanspoint and Zippy mentioned. Gatorade, Pedialyte, etc. In a pinch, soda (caffeine-free!) can be useful, because your blood sugar is probably crashing as well. Actually, even if you have access to Gatorade or whatnot, it's a good idea to eat some crackers or something else like that - carbs, salt, all the things that usually go missing when you've stopped ingesting stuff long enough to be dehydrated.

But to add to what SansPoint said: if you're not peeing several times throughout the day, you're not drinking enough.
posted by spaceman_spiff at 1:38 AM on March 15, 2008

I have waken up hungover, contacts still in, eyes feel like they have potato chips on them.

A glass of water is instant relief.

Dehydration, by definition is a lack of water. Your body needs that stuff and is especially adept at moving it where it needs to go. In my example, my eyes felt like new after a glass or two. Your heart, being essential and whatnot is surely high on the list.

They let you go after one bag of IV juice because they pumped you with 20+ oz. of H20. Urination will not occur unless you have sufficient water in your system or your body is filled with toxins (alcohol) that can't be removed otherwise.

You will be rehydrated when you have no thirst. Thirst is your body telling you that ingesting water is important at that particular moment. Drink water.

It isn't a complicated question. Drink water until you are no longer thirsty.

Gatorade is good when you sweat, which expels salts in the process. The salts are retained otherwise, so replenishing electrolytes is good after a workout, but not necessary if your problem is that you aren't ingesting enough water.
posted by clearly at 4:11 AM on March 15, 2008

Couple things.
A hangover is not *just* dehydration. It's also a loss of nutrients among which are the B vitamins. That's why Red Bull and its variants help so much with hangovers. And of course, water.
Gatorade was developed for hard-core athletes, then marketed to the rest of us schmos (kinda like how everyone *has* to have designer kitchens with butcher-block counters and triple-bowl sinks). For the exercise most of us do, Gatorade has too much sugar - though, if you're sugar crashing as well, it can be a good thing. Two different doctors I know have independently told me that Propel, without as many of the empty calories, is much better unless you react to the artificial sweeteners.

As far as the time it takes to rehydrate, I swam 1.5 miles before work the other morning. When I got to work, I'd forgotten about a scheduled drug testing. It took over 1.5 hours after drinking half a gallon (!) of water plus some propel before i had to pee at all.
posted by notsnot at 5:14 AM on March 15, 2008

This is another anecdotal rather than scientifical-based answer, but when I'm dehydrated, I'll drink about a pint of water, and I usually feel a sudden onrush of effects (anxiety and anger fading away, my body feeling more "well-oiled") within about five minutes of drinking. I don't know if that's what you'd consider "complete" rehydration after "complete" dehydration, though; those terms seem sorta relative.
posted by Greg Nog at 5:19 AM on March 15, 2008

I've been told that it actually takes several days to rehydrate fully after being dehydrated. So the water you drink the day BEFORE spin class actually matters.
posted by konolia at 5:38 AM on March 15, 2008

Anectodal, but one Judo teacher says 48 hours. Certainly the effects last longer than a day -- people who cut weight (a lot of water weight) the day before are still affected the day of competition.
posted by Comrade_robot at 5:42 AM on March 15, 2008

The fastest I've ever gotten fluids was 2L of Rengers in about 20 minutes, and the systemic effects were very rapid. Very, very rapid. I would assume the real answer is a couple hours for your body to actually absorb and make use of available fluid--but we're also not determining a basis for "Dehydrated"--which is affected by everything from weather to your gender and weight. Severe exposure dehydration would, I would assume, take several days of IV fluids administered slowly to bring you back to healthy.
posted by TomMelee at 6:10 AM on March 15, 2008

That's why Red Bull and its variants help so much with hangovers.

Red Bull can worsen hangovers or dehydration, as caffeine is a diuretic. Normally, it might not have much of an effect, but in light of the altered chemistry of the body (particularly the kidneys) during dehydration, Red Bull is a bad way to attempt rehydration.
posted by Inspector.Gadget at 9:00 AM on March 15, 2008

In strict medical terms (though even doctors screw this up all the time), there's a difference between "dehydration" and "hypovolemia;" the former is a loss of free water from total body water stores were as the latter is a loss of fluid volume (usually water and electrolytes) from extracellular fluid. Sometimes you can be both, but it's actually hypovolemia, particularly your circulating blood volume, that might cause your heart rate to go up.

There's no easy, short way to really answer your question without delving deep into physiology, but in handwaving terms: the rate at which one might correct hypovolemia using intravenous fluids is limited by how much volume is lost, whether there are ongoing losses, how well the patient's kidneys and heart function, and whether there are any electrolyte disturbances that might limit the rate of correction. For example, depending on the circumstances serum sodium levels may either be low or elevated, and replacing a patient's fluids too quickly or using the wrong concentration of fluids might actually cause too rapid a correction of the serum sodium, which might actually cause cerebral edema or osmotic demyelination syndrome -- both of which are very, very bad things. Or in an older patient or someone with known heart problems, aggressive rehydration might lead to pulmonary edema as the left side of the heart fails to keep up with the fluid being slammed into blood vessels and it ultimately backs up into the lungs.

If the circumstances are relatively optimal (say a young, otherwise healthy person who also has relatiely normal serum electrolytes), volume could potentially be corrected with IV fluids in minutes if necessary. With oral intake, we're talking probably a maybe 6-24 hours (don't quote me) I think, as water has to get to the colon for most of its absorption
posted by drpynchon at 10:12 AM on March 15, 2008 [2 favorites]

Just drink lots of water, or things with electrolytes in them.

Actually this should be AND, not or. The issue with dehydration in addition to what everone is saying is that if you rehydrate just by drinking a ton of water and then pee it all out again, you're not really doing much better. The tip they always stress at Burning Man is to intersperse water drinking with either electrolye-ish drinks like gatorade or something salty like miso soup. The people who were the sickest at Burning Man were the ones who just drank water and "got their electrolytes all out of wack" I am not a doctor, naturally.

When I've gone to give blood and was dehydrated enough that my already narrow veins were narrower, drinking a few glasses of water and waiting 15-20 minutes was enough to plump them up again.
posted by jessamyn at 11:26 AM on March 15, 2008

Actually this should be AND, not or.

Yes, this is so important. If you don't have Gatorade or anything like that then make sure that some of the water you take in has some salt in it. You don't want to just pound water as there are very serious, indeed deadly consequences of drinking too much water. Again IANAD.
posted by ob at 12:05 PM on March 15, 2008

I got seriously dehydrated last summer, and once I was back on my feet my doctor suggested a two-week period of being super conscientious about water intake plus drinking a bottle (I think they're a quart) of generic pedialyte per day. The generic is cheaper than the real thing, still costs more than gatorade, though. It tastes like crap - the "flavors" are kiddie-sweet, the "plain" is just unpleasant. Getting it super duper cold helps a lot, as does just steeling yourself and chugging it. If most of a day passed and I hadn't had the pedialyte, I felt bad, so I think it was a good idea. So, to answer your specific question, in my case, it took two weeks.
posted by donnagirl at 3:21 PM on March 15, 2008

An actual doctor recommended you taking a quart of pedialyte a day for 2 weeks? Ouchie---you don't usually see that. That really, REALLY surprises me.
posted by TomMelee at 3:33 PM on March 15, 2008

Hmm, maybe the bottles aren't a quart? It was a bottle, they're a standard size, I could be totally wrong about how much is in it. I'll stick by the "two weeks" part of my statement. Sorry to be fuzzy, maybe I'm dehydrated again.
posted by donnagirl at 8:04 PM on March 15, 2008

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