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Tachyphylaxis is a rapid decrease in response to a medicine or other biologically active substance after repeated or continuous exposure. The same dose produces less effect over a relatively short period. It is sometimes described as acute tolerance, although the terms are not identical in every context. The response can recover after the medicine is withheld, depending on the drug and mechanism.
read more about tachyphylaxis ...Tachyphylaxis can occur when receptors become desensitized, move away from the cell surface, or trigger weaker signals. It can also result from depletion of a stored neurotransmitter or mediator needed for the drug's effect. The body can activate opposing physiological responses that reduce the original action. The mechanism varies among medicines and can involve more than one process.
Tachyphylaxis has been described with indirect sympathomimetics, nitrates, topical nasal decongestants, and selected other medicines. Repeated ephedrine doses can become less effective as available norepinephrine stores decline. Continuous nitrate exposure can reduce the hemodynamic response unless an appropriate nitrate-free interval is used. Apparent loss of antidepressant benefit is also called tachyphylaxis in some literature, although relapse, nonadherence, or disease changes must be considered.
Tachyphylaxis develops rapidly, sometimes after only a few doses or a short period of continuous exposure. Tolerance commonly develops more gradually with repeated use over a longer time. Both result in a reduced response to the same dose, and the distinction is not always used consistently. Dependence is different and refers to physiological adaptation that can produce withdrawal when a drug is stopped.
Management depends on the medicine, clinical need, and suspected mechanism. Options can include allowing a drug-free interval, reducing exposure frequency, switching treatments, correcting administration problems, or treating the underlying condition differently. Simply increasing the dose can fail or increase toxicity. A clinician should first confirm adherence, diagnosis, interactions, and other reasons for reduced response.
No. Tachyphylaxis is a reduced physiological response after repeated exposure. Drug resistance usually describes microorganisms, cancer cells, or other targets that become less susceptible to treatment.
It can develop after several closely spaced doses or during continuous exposure, depending on the medicine. The defining feature is a relatively rapid decline in response.
Sometimes a larger dose produces a response, but it can also fail or increase adverse effects. Dose changes should be made only under clinical guidance.
The response can recover after a sufficient drug-free period when the underlying adaptation is reversible. Recovery time varies according to the drug and mechanism.
Tachyphylaxis. Medical Subject Headings (NCBI). https://www.ncbi.nlm.nih.gov/mesh?Cmd=DetailsSearch&Db=mesh&Term=%22Tachyphylaxis%22%5BMeSH+Terms%5D. Date Accessed August 6, 2026.
Ephedrine. StatPearls (NCBI Bookshelf). https://www.ncbi.nlm.nih.gov/books/NBK547661/. Date Accessed August 6, 2026.
Nitrates. StatPearls (NCBI Bookshelf). https://www.ncbi.nlm.nih.gov/books/NBK545149/. Date Accessed August 6, 2026.
Rhinitis Medicamentosa. StatPearls (NCBI Bookshelf). https://www.ncbi.nlm.nih.gov/books/NBK538318/. Date Accessed August 6, 2026.
Identification and Treatment of Antidepressant Tachyphylaxis. Innovations in Clinical Neuroscience (PubMed Central). https://pmc.ncbi.nlm.nih.gov/articles/PMC4008298/. Date Accessed August 6, 2026.