[1] It has a number of uses in medicine including cleaning wounds, removal and storage of contact lenses, and help with dry eyes.

Although neither of those names is technically accurate because normal saline is not exactly like blood serum, they convey the practical effect usually seen: good fluid balance with minimal hypotonicity or hypertonicity.

The amount of normal saline infused depends largely on the needs of the person (e.g. ongoing diarrhea or heart failure).

[17] The solution exerts a softening and loosening influence on the mucus to make it easier to wash out and clear the nasal passages for both babies[18] and adults.

[19] In very rare instances, fatal infection by the amoeba Naegleria fowleri can occur if it enters the body through the nose; therefore tap water must not be used for nasal irrigation.

Depending on the condition being treated, they may contain steroids, antihistamines, sympathomimetics, beta receptor blockers, parasympathomimetics, parasympatholytics, prostaglandins, non-steroidal anti-inflammatory drugs (NSAIDs), antibiotics or topical anesthetics.

Hypertonic saline—7% NaCl solutions are considered mucoactive agents and thus are used to hydrate thick secretions (mucus) in order to make it easier to cough up and out (expectorate).

3% hypertonic saline solutions are also used in critical care settings, acutely increased intracranial pressure, or severe hyponatremia.

[29] An 11% solution of xylitol with 0.65% saline stimulates the washing of the nasopharynx and has an effect on the nasal pathogenic bacteria.

William Brooke O'Shaughnessy, a recent graduate of Edinburgh Medical School, proposed in an article to medical journal The Lancet to inject people infected with cholera with highly oxygenated salts to treat the "universal stagnation of the venous system and rapid cessation of arterialisation of the blood" seen in people with severely dehydrated cholera.

[33] He found his treatment harmless in dogs, and his proposal was soon adopted by the physician Thomas Latta in treating people with cholera to beneficial effect.

Normal saline is considered a descendant of the pre-Ringer solutions, as Ringer's findings were not adopted and widely used until decades later.

The term "normal saline" itself appears to have little historical basis, except for studies done in 1882–83 by Dutch physiologist Hartog Jacob Hamburger; these in vitro studies of red cell lysis suggested incorrectly that 0.9% was the concentration of salt in human blood (rather than 0.6%, the true concentration).

[35] Normal saline has become widely used in modern medicine, but due to the mismatch with real blood, other solutions have proved better.

The 2018 publication of a randomized, controlled trial with 15,000 people in intensive care units showed that compared to normal saline, lactated Ringer's solution reduced the combined risk of mortality, need for additional dialysis, or persistent kidney problems from 15% to 14%, which given the large number of patients is a significant reduction.