Editor’s Capsule Summary
What is already known on this topic
Latrodectus (black widow) spider bite may cause a painful systemic myopathic syndrome (latrodectism). Existing immunoglobulin-based antivenom is limited in supply and associated with anaphylaxis.
What question this study addressed
Is a newer antibody-based antivenom (antivenin Latrodectus equine immune F[abʹ]2) safe and efficacious in the treatment of black widow spider envenomation?
What this study adds to our knowledge
In this multicenter randomized trial of 60 patients, F(abʹ)2 was associated with fewer treatment failures (<13-mm visual analog scale pain scale decrease, need for commercial antivenom, or need for prescription analgesia) than placebo (51.7% versus 77.4%). Adverse event rates were similar.
How this is relevant to clinical practice
F(abʹ)2 offers a potential new treatment for Latrodectus envenomation. Larger series are needed to verify its safety and effectiveness. Future studies must develop improved methods for defining latrodectism cases and treatment outcomes.