Brown Recluse Spider Envenomation Medication

Updated: Oct 14, 2021
  • Author: Thomas C Arnold, MD, FAAEM, FACMT; Chief Editor: Joe Alcock, MD, MS  more...
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Medication

Medication Summary

Use tetanus prophylaxis, analgesics, and antipruritics as needed. Reserve antibiotics for evidence of true infection and do not administer prophylactically. Carlton recommends antihistamines and observation alone as treatment for brown recluse spider bites. [18]

No commercial antivenom for loxoscelism is currently approved for use in the United States. A horse-derived FAB antivenom is available in Argentina, Peru, Brazil, and Mexico, and it is indicated for cutaneous loxoscelism and cutaneous hemolytic manifestations. [9, 19] It is only a matter of time before a suitable antivenom may be available in the United States.

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Antibiotics

Class Summary

Antibiotics should not be used prophylactically.  It has been suggested that antibiotics may minimize the local inflammatory component of cutaneous loxoscelism and decrease resulting skin necrosis.

Dapsone (Avlosulfon)

Dapsone is bactericidal and bacteriostatic against mycobacteria strains. The mechanism of action is similar to that of sulfonamides where competitive antagonists of p-aminobenzoic acids (PABA) prevent the formation of folic acid, causing bacterial growth inhibition.

If used, initiate the treatment with small doses followed by gradual increments. Monitor patients carefully because hypersensitivity, methemoglobinemia, and hemolysis in the presence of G-6-PD deficiency have been reported.

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Corticosteroids

Class Summary

These agents have anti-inflammatory properties and cause profound and varied metabolic effects. In addition, these agents modify the body's immune response to diverse stimuli.

Use of corticosteroids is controversial in brown recluse spider bites. Evidence for using corticosteroids is insufficient.

Methylprednisolone (Solu-Medrol)

Methylprednisolone decreases inflammation by suppressing the migration of polymorphonuclear leukocytes and reversing increased capillary permeability.

Prednisone (Deltasone, Orasone, Meticorten)

Prednisone decreases inflammation by suppressing the migration of polymorphonuclear leukocytes and reversing increased capillary permeability.

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Antihistamines

Class Summary

Antihistamines are used to treat minor allergic reactions and anaphylaxis. Diphenhydramine may be used to pretreat patients with prior documentation of minor allergic reactions. These agents may control itching by blocking effects of endogenously released histamine.

Diphenhydramine (Benadryl)

Diphenhydramine is used for symptomatic relief of allergic symptoms caused by histamine released in response to allergens.

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