Seizures during alpha interferon therapy

Alpha interferon is now used widely in the therapy of chronic viral hepatitis. The common side effects of interferon are well known; the uncommon side effects are less well defined. We have evaluated the incidence and characteristics of seizures that occurred during alpha interferon therapy. Methods: A retrospective chart review was done on 311 patients with chronic hepatitis treated with alpha interferon between 1983 and 1994 at the National Institutes of Health. Results: Four of 311 patients (1.3%) developed grand mal seizures while on therapy with alpha interferon. Three patients had chronic hepatitis B (two had an accompanying glomerulonephritis) and one chronic delta hepatitis. Interferon had been given in doses of 5–10 million units each day or three times weekly for 2–14 months before the onset of seizures. No other obvious cause for seizures was identified. Seizures resolved once interferon was stopped, and did not recur even without chronic anticonvulsant therapy. Conclusions: Alpha interferon in the doses used to treat chronic viral hepatitis caused seizures in approximately 1% of patients.