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Anticonvulsant Hypersensitivity Syndrome

Background: Anticonvulsant hypersensitivity syndrome (AHS) is a serious but poorly understood and little known disease. It has been variously described in the literature since 1934. Fatalities are rare but have been reported. Methods: A MEDLINE search was undertaken from 1991 to present, using the keywords “anticonvulsant,” “phenytoin,” and “hypersensitivity.” English language articles and their endnotes were reviewed, and neurologists, dermatologists, and specialists in hematology-oncology were consulted. Results: A case of AHS is described. Investigators have reported epidemiologic data and described the pathophysiology, diagnostic criteria, and management options. Conclusions: Family physicians should be aware of the AHS because of the high likelihood that patients with this syndrome will come first to their primary care physicians for care. Certain anticonvulsant medications have a high degree of cross-reactivity, the incidence of AHS is higher among first-degree relatives, and the disorder mimics systemic infection. If AHS is suspected, the antiepileptic drug should be discontinued. Supportive care should be directed to the appropriate organ systems, with particular attention to skin, eyes, and liver. Corticosteroid treatment might be effective in reversing the drug reactions, but it is not recommended in cases of suspected or actual infection because of the increased risk of immunocompromise, sepsis, and associated mortality.