effect of drinking sea water

Human Fluid Ratio: 60:40:20 rule

ECF : ICF = 2:1

When consuming sea water (= salt),

When entering the body, hypertonic solution introduced into the ECF. Water in ICF will flow out to the ECF compartment. Solutes remain in the ECF. Thus we will get dehydrated when consuming to much sea water.

If you have only seawater to drink, and you keep drinking it, you become more and more dehydrated and start to suffer the symptoms of that:

-- Thirst
-- Loss of appetite
-- Dry skin
-- Reduced urine volume, and it's darker than usual
-- Sleepiness

If you continue, you'll likely get:
-- Headaches
-- Dry mouth
-- Low blood pressure
-- Rapid heart rate
-- Dizzyness or fainting when you suddenly stand up

If you still keep going, it gets worse:
-- Delirium, imagining things that aren't there, etc.
-- Unconsciousness or seizures
-- Death, if you don't receive medical treatment

By the time you've lost about 15% of your body's water, it's usually fatal.

Your body normally has good reserves of water in its tissues, to make up losses from breathing, sweating, etc. So if a healthy person drinks a little seawater it's probably not going to hurt anything from a dehydration standpoint. Some authorities say an adult in good health can probably drink up to a litre of seawater a day, IF he also drinks lots of fresh water so his body can properly dilute the seawater and get it out of his body without needing to pull water from the body's cells for that.