Physicians who prescribe viscous lidocaine preparations should be aware of the adverse effects and the high risk for overdose in pediatric patients. Owing to altered pharmacokinetics (increased absorption, decreased clearance, and prolonged half-life), doses that are innocuous for adults may present a significant potential toxic hazard in children. Lidocaine should not be used to treat painful mouth lesions in children until further safety data are available. Benzocaine may be considered as a safe alternative to lidocaine. Its low incidence of side effects makes it a safer choice for infants and children. If no other choices are appropriate, then very specific instructions should be given to parents. The amount, frequency, maximum daily dose, and mode of administration should be clearly communicated (eg, cotton pledget to individual lesions, one-half dropper to each cheek every four hours, or 20 minutes before meals). They should never be prescribed on a "PRN" basis.