Eli5: Why does an IV of fluids make you feel so much better than drinking the same amount of fluids?

Question

I know it goes into your body faster but an IV seems to make me feel miraculously better even if I drink fluids and wait.

In: 21

Answer 1

Pretty simple – no digestion lag. If you’re dehydrated and feeling bad (thirsty, dry mouth, headache), what you’re lacking is fluid in circulation. IV is going straight into circulation and works fast as it goes in pretty much to bring up blood pressure. Drinking requires that water to pass into your gut and get absorbed, and that takes a bit of time. It also requires a gut that’s working well, so if you’ve got gastro or are in shock you’re not likely to be absorbing optimally, even if you can keep it down.