What does hypertonic mean?
Hypertonic is a technical adjective describing a condition of greater concentration or tension than expected. In chemistry and medicine, a hypertonic solution contains more dissolved solute than the surrounding or reference solution. Because water tends to move by osmosis toward the higher solute concentration, hypertonic fluids can draw water into cells or tissues. In clinical descriptions of muscle function, hypertonic describes muscles with excessive tone, meaning they are unusually stiff, tense, or resistant to relaxation. The term is widely encountered in discussions of intravenous fluids, cellular physiology, and neurological or physical rehabilitation. It should not be confused with hypotonic, which indicates a lower solute concentration. Although the pronunciation and spelling are consistent in British and American English, context determines whether the word is being used primarily in a chemical sense or a muscular one.
adjectiveHypertonic describes a solution whose solute concentration is greater than that of a reference solution, causing water to move into it by osmosis. In medicine, it describes excessive muscle tone, in which muscles are unusually stiff or resistant to relaxation.
- Having a higher solute concentration and osmotic pressure than a reference solution.
- Characterized by excessive muscle tone, stiffness, or resistance to relaxation.
"The clinician used a hypertonic saline solution to reduce swelling in the patient's brain."
"Water moved out of the cells and into the hypertonic intravenous fluid."
"The patient experienced painful hypertonic muscles after the procedure."
Hypertonic means “too tense”: in a solution, too concentrated; in the body, too stiff.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does hypertonic come from?
The word combines the Greek-derived prefix hyper-, meaning “over” or “excessive,” with tonic, which comes from Greek tonikos, related to tonos, “tone” or “tension.” It entered English in the 19th century in the sense of excessive tension before becoming established in scientific descriptions of solutions and muscle tone. The same roots also underlie terms such as hypertension and hypertrophic, while tonic preserves the idea of muscular or elastic tension.
Related word forms
How hypertonic is actually used
The term is most common in medicine, biology, and chemistry. In pharmacology, “hypertonic” usually describes a solution more concentrated than body fluids; in neurology and rehabilitation, it describes increased muscle tone.
Easily confused with hypertonic
A hypertonic solution has a higher solute concentration than the solution it is compared with, whereas a hypotonic solution has a lower solute concentration.