Choosing Wisely:

Don’t use phenytoin or fosphenytoin to treat seizures caused by drug toxicity or drug withdrawal.

Rationale and Comments: With rare exceptions, phenytoin is ineffective for convulsions caused by drug or medication toxicity. Phenytoin has been demonstrated to be ineffective for the treatment of isoniazid-induced seizures and withdrawal seizures and may potentially be harmful when used to treat seizures induced by theophylline or cyclic antidepressants. First-line treatment of toxin-induced seizures and withdrawal seizures is benzodiazepines, followed by additional medications that act through agonism at the γ-aminobutyric acid A receptor, such as barbiturates.
Sponsoring Organizations:
  • American College of Medical Toxicology
  • American Academy of Clinical Toxicology
  • Sources:
  • Expert consensus
  • Disciplines:
  • Neurologic
  • Emergency medicine
  • References: • Goldberg MJ, Spector R, Miller G. Phenobarbital improves survival in theophylline-intoxicated rabbits. J Toxicol Clin Toxicol. 1986;24(3):203–11.
    • Blake KV, Massey KL, Hendeles L, Nickerson D, Neims A. Relative efficacy of phenytoin and phenobarbital for the prevention of theophylline-induced seizures in mice. Ann Emerg Med. 1988 Oct;17(10):1024–8.
    • Miller J, Robinson A, Percy AK. Acute isoniazid poisoning in childhood. Am J Dis Child. 1980 Mar;134(3):290–2.
    • Saad SF, el-Masry AM, Scott PM. Influence of certain anticonvulsants on the concentration of gamma-aminobutyric acid in the cerebral hemispheres of mice. Eur J Pharmacol 1972 Mar;17(3):386–92.
    • Okamoto M, Rosenberg HC, Boisse NR. Evaluation of anticonvulsants in barbiturate withdrawal. J Pharmacol Exp Ther. 1977 Aug;202(2):479–89.
    • Chance JF. Emergency department treatment of alcohol withdrawal seizures with phenytoin. Ann Emerg Med. 1991 May;20:520–2.
    • Sharma AN, Hoffman RJ. Toxin-related seizures. Emerg Med Clin North Am. 2011 Feb;29(1):125-39.
    • Hung OL, Shih RD. Antiepileptic drugs: the old and the new. Emerg Med Clin North Am. 2011 Feb;29(1):141-50

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