If drinking salt water further dehydrates the body, why is saline used to treated dehydration?
Amount of sodium is the biggest factor. Saline is purified water with a small amount of sodium chloride. Sea water is a high amount of sodium.
False premise. Drinking salt water doesn’t *necessarily* dehydrate the body. It’s just that to avoid that particular effect, you have to drink much smaller quantities *at a time*, more consistently over long periods of time.
Normal saline is 0.9% sodium chloride.
That’s 9 grams of NaCl in one liter of water. This is isotonic to your blood.
Sea water has ~35 grams per liter, almost 4 times as much.
Its all about concentration. Saline is meant to match the body’s natural level of electrolytes. It’s the same reason sport drinks like Gatorade contain electrolytes. They can replenish fluid levels without disrupting the electrolytes balance.
Salt water is too salty and saline is just right.
When you are dehydrated you also lose salts/electrolytes which are not exactly the same as sea water, for example.