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Obese Man With Severe Pain and Swollen Hand

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Brown recluse bite is diagnosed based on history and clinical presentation and, when possible, identification of the spider. However, patients often do not realize they have been bitten before they develop symptoms, making it impossible to confirm the etiology of the lesion. It is often helpful to ask the following questions during the assessment

  • Did you feel the bite take place?
  • Did you see or capture the spider? If so, can you describe it?
  • Where were you when the spider bit you?
  • Did you recently clean any clutter or debris?

Furthermore, patients who recall seeing a spider after being bitten typically do not bring the arachnid to their health care facility. Another complicating factor is the numerous possible causes of necrotic skin lesions that can be mistaken for spider bites.5 The differential diagnosis can include allergic dermatitis, cellulitis, methicillin-resistant Staphylococcus aureus (MRSA) infection, skin abscesses, other arthropod bites, necrotizing fasciitis, or bee sting.


One of the most important factors in successful treatment is timeliness of medical attention after the initial bite; because the most damaging tissue effects occur within the first three to six hours after envenomation, intervention during this time is imperative.8 Initial treatment of cutaneous brown recluse spider bite is often conservative, given the variation in clinical presentation, inability to predict the future extent of lesions, and lack of evidence-based treatment options.9 The goals of therapy are to ensure that skin integrity is maintained, infection is avoided, and circulation is preserved.10

Nonpharmacologic treatments for brown recluse spider bite consist of cleaning the wound, treating the bite area with “RICE” (rest-ice-compression-elevation) therapy during the first 72 hours to reduce tissue damage, and ensuring adequate hydration.1,10-13 The affected area should be cleaned thoroughly; infected wounds require topical antiseptics and sterile dressings. Applying a cold compress to the bite area at 20-minute intervals during the first 72 hours after envenomation has been shown to reduce tissue damage.10 Heat should not be applied to the area, as it may increase tissue damage.

Pharmacologic treatment. Patients who experience systemic symptoms such as nausea, vomiting, pain, fever, and pruritus should be provided antipyretics, hydration, and analgesics for symptomatic relief, as needed.9 Antihistamines and benzodiazepines have been found to be useful in relieving symptoms of anxiety and pruritus. To help manage mild pain, OTC NSAIDs are recommended.10

If the date of the last tetanus shot is unknown, a prophylactic tetanus booster (tetanus/diphtheria [Td] or TDaP) should be administered.10 The prophylactic use of cephalosporins to treat infection is indicated in patients with tissue breakdown.1

Among the more controversial treatment choices are use of corticosteroids and dapsone, prescribed frequently in the past. Use of oral corticosteroids for cutaneous forms of spider bite is not supported by current evidence.5,10,14 Research does, however, support their role in the treatment of bite-induced systemic illness, particularly for preventing kidney failure and hemolysis in children.1,15

Dapsone, prescribed for the necrotic lesions, may be useful in limiting the inflammatory response at the site of envenomation.1,3 However, human studies have shown conflicting results with dapsone administration, with some demonstrating no improvement in patient outcomes.8 The risks of dapsone’s many adverse effects, including dose-related hemolysis, sore throat, pallor, agranulocytosis, aplastic anemia, and cholestatic jaundice, may outweigh its benefits.1,12 Furthermore, dapsone treatment is restricted in patients with G6PD (glucose-6-phosphate dehydrogenase) deficiency because of their increased risk for hemolytic anemia.1 Accordingly, dapsone is recommended only for moderate-to-severe or rapidly progressing cases in adults.1


A patient's follow-up care should be assessed individually, based on the nature of his/her reaction to the bite. In all instances, however, ask the patient to report worsening of symptoms and changes in the skin around the bite area; if systemic symptoms develop, patients should proceed to the ED. If, after six to eight weeks, the necrotic lesion is large and has stabilized in size, consider referring to a wound care clinic for surgical excision of the eschar.9

To avoid future spider bites, advise patients to clear all clutter, move beds away from the wall, remove bed skirts or ruffles, avoid using underbed storage containers, avoid leaving clothing on the floor in piles, and check shoes before dressing.5

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