If you added distilled water it would flood into the cells that it comes into contact with. The cells in the blood would swell and lyse, leading to massive anemia, then tissue death and eventually death.
Health Medical Pharma
In medicine, saline (also saline solution) is a general phrase referring to a sterile solution of sodium chloride (NaCl, more commonly known as salt) in water, but is only sterile when it is to be placed parenterally (such as intravenously); otherwise, a saline solution is a salt water solution. The sterile solution is typically used for intravenous infusion, rinsing contact lenses, nasal irrigation, and often used to clean a new piercing. It is also a good medium to store an avulsed ("knocked out") tooth until it can be re-implanted by a dentist. Saline solutions are available in various formulations for different purposes. Salines are also used in cell biology, molecular biology, and biochemistry experiments.