Calc Function

    • Calcs that help predict probability of a diseaseDiagnosis
    • Subcategory of 'Diagnosis' designed to be very sensitiveRule Out
    • Disease is diagnosed: prognosticate to guide treatmentPrognosis
    • Numerical inputs and outputsFormula
    • Med treatment and moreTreatment
    • Suggested protocolsAlgorithm





    Chief Complaint


    Organ System


    Patent Pending

    Antivenom Dosing Algorithm

    Doses antivenom (CroFab only, not Anavip) for pit viper snakebites.


    This dosing tool is intended to assist with calculation, not to provide comprehensive or definitive drug information. Always double-check dosing of any drug and consult a pharmacist when necessary.


    Use only in cases of symptomatic crotalid snake envenomation (pit vipers including rattlesnakes, cottonmouths, and copperheads) in the US, for CroFab administration. Do not use in cases of coral snake envenomation or snakes not indigenous to the US. Do not use for Anavip administration, as it will result in incorrect dosing. Report all cases of suspected/confirmed envenomation to poison control (1-800-222-1222).

    When to Use
    Why Use
    • Patients with known or suspected crotaline envenomation (rattlesnake, copperhead, cottonmouth).
    • Not valid for snakebites to the head or neck or with cardiovascular collapse: call Poison Control (1-800-222-1222).
    • Based on the Unified Treatment Algorithm (Lavonas 2011), which was developed with the goal of quick identification and management of patients who may benefit from Crotalidae Polyvalent Immune Fab.
    • There is significant variability among envenomation patients, and this algorithm does not represent a standard of care.
    • Report all cases of suspected/confirmed envenomation to poison control (1-800-222-1222).
    • Approximately 9,000 snakebites are treated yearly in the US, with 5 of those patients dying annually. The case-fatality rate is reported at 1 death per 736 patients.
    • The algorithm specifies the manifestations of crotaline envenomation that necessitate aggressive management.


    Please fill out required fields.

    Next Steps
    Creator Insights
    Dr. Eric J. Lavonas

    About the Creator

    Eric J. Lavonas, MD, is a practicing emergency physician and medical toxicologist. He is a professor of emergency medicine at the University of Colorado School of Medicine, and has served as the interim director of the emergency department at Denver Health. His research interests include envenomation and antidote development, carbon monoxide poisoning, and health care quality.

    To view Dr. Eric J. Lavonas's publications, visit PubMed

    Content Contributors
    • Stephen A. Harding, MD
    About the Creator
    Dr. Eric J. Lavonas
    Partner Content
    Content Contributors
    • Stephen A. Harding, MD