What does tachyphylaxis mean?
Tachyphylaxis is the rapid loss or reduction of a person's response to a drug or treatment after repeated exposure. It is especially used in pharmacology and medicine, where a treatment that initially produces a strong effect may become progressively less effective after successive doses. The term is narrower than tolerance: ordinary tolerance often develops gradually and may accompany long-term use, whereas tachyphylaxis describes a comparatively swift decline in responsiveness. Tachyphylaxis can apply to many physiological responses, not only to medicines, but it is most commonly discussed in connection with repeated drug dosing. Recognizing the phenomenon is clinically useful because increasing the dose may not restore the original response and could expose a patient to unnecessary risk. The word combines Greek elements meaning “fast” and “protection,” reflecting the early scientific idea of a rapidly developing protective resistance.
nounA rapid reduction in the response to a repeated dose of a drug or other treatment. It differs from ordinary tolerance, which generally develops more gradually.
- The rapid decrease in responsiveness to a drug or other treatment following repeated administration.
"The clinician noted tachyphylaxis after several doses of the medication produced progressively weaker effects."
"Repeated administration led to tachyphylaxis, so the later doses had little effect."
"The researchers measured tachyphylaxis as the response weakened over successive injections."
The plural is uncommon in general writing but may be used when discussing distinct instances or types of the condition.
"The study reported tachyphylaxes in several experimental models."
Tachyphylaxis is tolerance in fast motion: the effect can fade after remarkably few doses.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does tachyphylaxis come from?
Tachyphylaxis was formed in the late nineteenth century from Greek roots meaning “fast” and “protection.” The suffix is based on Greek phylax, meaning a guard or protector, related to phylaxis. Its earliest medical sense concerned the rapid loss of a physiological response to repeated exposure, and the term later became especially important in pharmacology.
Related word forms
How tachyphylaxis is actually used
This is primarily a medical and pharmacological term. It is not a synonym for every form of drug tolerance, because it specifically emphasizes the speed at which responsiveness diminishes.
Easily confused with tachyphylaxis
Tolerance is a general decrease in response to repeated exposure, whereas tachyphylaxis specifically describes a rapid loss of effect that can occur after only a few administrations.
Tachyphylaxis is a diminishing response to treatment, while anaphylaxis is a severe, potentially life-threatening allergic reaction.