phe·​nyt·​o·​in fə-ˈni-tə-wən How to pronounce phenytoin (audio)
: a crystalline anticonvulsant compound C15H12N2O2 used in the form of its sodium salt in the treatment of epilepsy

called also diphenylhydantoin

Examples of phenytoin in a Sentence

Recent Examples on the Web Epilepsy typically is treated with anti-epileptic drugs (AEDs) such as Topamax (topiramate), Tegretol (carbamazepine), Lamictal (lamotrigine), or Dilantin (phenytoin). Diana Apetauerova, Verywell Health, 24 July 2023 The results also showed expected damage to the cerebellum caused by the anti-epileptic drug phenytoin, which he was required to take throughout his life, as well as other damage typical of ageing. Alison Abbott, Scientific American, 30 Jan. 2014 In the effluent from the Morgantown wastewater plant, the USGS team found high concentrations of three drugs in addition to phenytoin. Natasha Gilbert, STAT, 11 Dec. 2019 Three years later, Snyder, whose team tested both raw and drinking-water samples at 18 U.S. sites, added ibuprofen, meprobamate (an antianxiety medication), and phenytoin (another antiseizure drug), along with other pharmaceuticals, to the list. Rachael Moeller Gorman, Good Housekeeping, 15 Aug. 2012

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'phenytoin.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History



First Known Use

1941, in the meaning defined above

Time Traveler
The first known use of phenytoin was in 1941

Dictionary Entries Near phenytoin

Cite this Entry

“Phenytoin.” Dictionary, Merriam-Webster, Accessed 26 Feb. 2024.

Medical Definition


phe·​nyt·​o·​in fə-ˈnit-ə-wən How to pronounce phenytoin (audio)
: an anticonvulsant used often in the form of its sodium salt C15H11N2NaO2 to prevent or treat seizures

called also diphenylhydantoin

see dilantin

More from Merriam-Webster on phenytoin

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