In patients with bites from North American pit vipers, antivenom should be given if there is evidence of severe systemic envenomation or rapidly increasing or major local swelling, especially if there is blistering or bleb formation. Shock is especially serious in children, and aggressive fluid resuscitation is often needed. The onset of any of these symptoms is an indication for urgent administration of antivenom. 15 , 17 Mild swelling in the absence of systemic envenomation is not an indication for antivenom. In patients with coral snakebites, any degree of flaccid paralysis warrants antivenom therapy.