HYPOTONIC, Isotonic & Hypertonic

The more ingredients that are added into a solution (electrolytes, sugar, vitamins, minerals etc), the thicker it’s concentration becomes and the slower it is absorbed into the body.

Osmolality is a measurement of a fluids concentration which is represented by the number of solutes per volume of fluid. The osmolality of the blood and body fluids is approximately 290 mOsmol/L.

  • Hypertonic solutions have an osmolality higher than the body (> 300 mOsmol/l)
  • Isotonic solutions have an osmolality similar to the body (= 290 mOsmol/l)
  • Hypotonic solutions have an osmolality lower than the body (< 280 mOsmol/l) which actively promotes fluid absorption.


Tonicity refers to the concentration of a solution and the osmotic pressure gradient that this creates across a semipermeable membrane (like the gut). This in turn determines in what direction water will move across that membrane with water moving from low concentration solutions to high concentration solutions to try and to maintain equilibrium.

Electrolyte Balance

If an electrolyte fluid is Hyper-tonic (high concentrations) water will be pulled out of the body and drawn into the gut to dilute that solution back to an Iso-tonic state.
HYPOTONIC Solutions have a lower concentration of electrolytes than the body which allows the solution to be absorbed faster than hypertonic and Isotoinc drinks or plain water. This rapid absorption into the body prevent dehydration more effectively and helps avoid that bloated feeling in the stomach when fluids are not absorbed quickly.Because of the effectiveness of hypotonic solutions, they are commonly used to give fluids intravenously to hospitalised patients in order to treat or avoid dehydration.

Aqualyte is a HYPOTONIC Solution with an osmolality of 150 mOsmol/L which promotes rapid fluid absorption helping to prevent dehydration and it’s affects on health and performance.