Neonatal mydriasis: intravenous lidocaine adverse reaction.

Lidocaine (a sodium channel blocker) serves as an antiepilepsy drug in neonates. We present a neonate with a seizure disorder who acutely developed pupillary mydriasis secondary to lidocaine overdose. We suggest adding this side effect to the list of untoward effects of lidocaine and to the differential diagnosis of fixed dilated pupils in neonates treated with lidocaine.