Skip to main content

Antivenin Latrodectus Mactans (Black Widow Spider Antivenin) Shortage

Last Updated: August 6, 2025
Status: Resolved

Products Affected - Description
    • Antivenin Lactrodectus Mactans (Black Widow Spider Antivenin) powder for solution for injection, Merck, 6000 units, vial, 1 count, NDC 00006-5424-02
Reason for the Shortage
    • Merck has low inventory of Antivenin Latrodectus Mactans. They could not provide a reason for the shortage.
Available Products
    • There is insufficient supply for usual ordering

Estimated Resupply Dates

    • Merck is accepting drop ship orders for a maximum of 2 doses at a time. Merck could not provide an estimate for when supply will improve.

Implications for Patient Care

    • Merck is the sole supplier of Antivenin Latrodectus Mactans
    • Antivenin latrodectus is used to treat envenomation from black widow (Latrodectus mactans) bites. [1]

Safety

    • Reserve antivenin for patients presenting with severe symptoms who are refractory to supportive care. Additional priority may be given to children and older adults with comorbidities. [2]
    • Antivenin Latrodectus is associated with anaphylaxis in up to 5% of patients.[2 3]
    • History of asthma and atopy are considered contraindications to receiving Antivenin latrodectus. [3 4]

References

    1. Antivenin (Latrodectus mactans). UpToDate Lexidrug, Lexi-Drugs Online. Waltham, MA, 2023.
    2. Herness J, Snyder MJ, Newman RS. Arthropod Bites and Stings. American family physician 2022;106(2):137-47
    3. Williams M, Sehgal N, Nappe TM. Black Widow Spider Toxicity. StatPearls. Treasure Island (FL) ineligible companies.: StatPearls Publishing
    4. Caruso MB, Lauria PSS, de Souza CMV, Casais ESLL, Zingali RB. Widow spiders in the New World: a review on Latrodectus Walckenaer, 1805 (Theridiidae) and latrodectism in the Americas. The journal of venomous animals and toxins including tropical diseases 2021;27:e20210011 doi: 10.1590/1678-9199-jvatitd-2021-0011[published Online First: Epub Date]|.

Updated

Updated August 6, 2025 by Rachael Freeman, PharmD, BCPS. Created March 5, 2009 by Jane Chandramouli, PharmD, Drug Information Specialist. © 2025, Drug Information Service, University of Utah, Salt Lake City, UT.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.