ELI5: Why is it so painful to rub salt on a open wound?

The other answers here are great! They explain the pain part of things much better than I can. To add to that, on a cellular level salt can literally pull water out of your cells and tear them apart. This has to do with PH balance, or how acidic or alkaline a liquid is. When you get an IV at the hospital they give you saline in or basically salt water in a low amount, because if they gave you regular water your blood cells would absorb too much water and explode since it’s the wrong pH balance. The salt in the saline stops this from happening too quickly. Saline has the same pH balance as our blood, so we can absorb water through our blood easily, but not too fast. If the saline has too much salt, then the water from the cells will be sucked out from the inside, causing the blood cell to burst.

/r/explainlikeimfive Thread