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Envenomation from most species of spiders in the United States causes only
Local pain
Redness, swelling
Venomous black widow spiders (Latrodectus mactans) cause
Brown recluse spider (Loxosceles reclusa) causes
Stings by most scorpions in United States cause only local pain
Stings by the more toxic Centruroides species (found in southwestern United States) may cause
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Black Widow Spider Bites
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Relieve pain with parenteral opioids or muscle relaxants (eg, methocarbamol, 15 mg/kg)
Calcium gluconate 10%, 0.1–0.2 mL/kg intravenously, may relieve muscle rigidity
Antivenom is available; because of concerns about acute hypersensitivity reactions, it is often reserved for very young or older adult patients and those who do not respond to the above measures
Horse serum sensitivity testing required (instruction and testing materials are in the antivenin kit)
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Brown Recluse Spider Bites
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