A common example of an isotonic solution is saline solution. Normal saline solution contains 0.9% sodium chloride and is primarily used as intravenous fluid in medical settings.
A solution is a combination of two or more substances. An isotonic solution is a combination of two or more solutions that have the same or similar concentration. For instance, isotonic solutions have the same salt concentration as human blood and body cells, allowing the cells' fluid levels to remain balanced. Cells do not lose fluid or swell with fluid when in the presence of an isotonic solution. Isotonic solutions delivered intravenously are used to replenish fluid levels in dehydrated patients; they are also used to administer vaccines safely and effectively.