What is the treatment for a brown recluse spider bite?

Treatment of Brown Recluse Spider Bites

Emergency services should be called if a person bitten by a brown recluse spider develops systemic symptoms such as difficulty breathing, muscle rigidity, dizziness, or confusion. 1

Initial Assessment and Management

When to Seek Medical Care

• Seek immediate medical attention if:
  • Pain extends beyond the bite site
  • Pain becomes severe and uncontrolled with over-the-counter medications
  • An open wound develops
  • Systemic symptoms develop (fever, rash, muscle pain, hemolysis) 1

First Aid Measures

• Clean the wound thoroughly with soap and water 2
• Apply cold compresses to reduce inflammation (10-15 minutes several times daily) 2
• Elevate the affected area if significant swelling is present 2
• Use over-the-counter acetaminophen or NSAIDs for pain relief 1, 2

Medical Treatment

Pain Management

• Over-the-counter acetaminophen and NSAIDs for pain control 1
• If skin is intact, topical lidocaine (4-5%) can help with pain relief 1

Wound Care

• Regular wound cleaning and appropriate dressings 2
• Avoid early surgical intervention - surgical excision is only indicated for lesions that have stabilized and are no longer enlarging 3
• Delay surgery for several weeks if needed, as premature debridement may worsen outcomes 4

Medication Options

1. Antibiotics:

   • Recommended if signs of secondary infection develop
   • Choose antibiotics active against staphylococci and streptococci:
     • Cephalexin 500 mg four times daily for 5 days
     • Clindamycin 300-450 mg three times daily for 5 days (for penicillin-allergic patients)
     • Amoxicillin/clavulanic acid 875/125 mg twice daily for 5 days 2

2. Corticosteroids:

   • Consider for severe local reactions or systemic loxoscelism
   • Short course of prednisone (40mg daily for 7 days) for severe swelling 2
   • Caution: Some evidence suggests systemic corticosteroids may delay healing in localized bites 5

3. Dapsone:

   • May be considered for necrotic arachnidism in adults
   • Must screen for glucose-6-phosphate dehydrogenase deficiency before use
   • Caution: Associated with slower healing and increased scarring in some studies 5, 3

4. Other treatments:

   • Antihistamines for pruritus 2
   • Topical hydrocortisone (0.5-1%) for local inflammation 2

Monitoring and Follow-up

• Re-evaluate within 48-72 hours if no improvement is seen 2
• Monitor for signs of:
  • Expanding necrosis (brown recluse bites can cause necrotic wounds that progress over days to weeks) 1
  • Hemolysis or rhabdomyolysis (rare systemic complications) 1
  • Secondary infection

Special Considerations

Indications for Hospitalization

• Suspected deep necrotizing infection
• Systemic signs of infection (fever, tachycardia)
• Systemic loxoscelism with hemolysis
• Failure of outpatient treatment 2

Advanced Treatment Options

• For non-healing wounds (2-3 months after conventional treatment failure), hyperbaric oxygen therapy (HBOT) may be considered 6
• HBOT at 2 ATA (atmospheres absolute) with 100% oxygen has shown benefit even months after the bite 6

Prognosis

• Most brown recluse spider bites heal without significant complications
• Median healing time is approximately 17 days
• Approximately 21% of bites result in permanent scarring 5
• Factors associated with slower healing include:
  • Higher severity at presentation
  • More erythema and necrosis
  • Older age
  • Diabetes
  • Delayed medical attention 5

Common Pitfalls to Avoid

1. Premature surgical debridement (wait until the lesion has stabilized)
2. Overdiagnosis of brown recluse bites in non-endemic areas
3. Failure to recognize systemic symptoms requiring emergency care
4. Using dapsone without screening for G6PD deficiency
5. Relying on unproven treatments without addressing basic wound care principles