What is the treatment for a brown recluse spider bite?

Treatment for Brown Recluse Spider Bite

The primary treatment for brown recluse spider bites is supportive care with rest, ice compresses, elevation, over-the-counter analgesics, and delayed surgical debridement only after the wound has stabilized—antibiotics are not routinely indicated unless secondary bacterial infection develops. 1

Initial Wound Care and First Aid

• Thoroughly irrigate the bite wound with copious amounts of warm or room temperature water until no foreign matter remains in the wound 2, 1
• Apply ice with a clean barrier between ice and skin for local pain relief 2, 1
• Elevate the affected extremity to reduce swelling and accelerate healing 1
• Remove rings and other constricting objects immediately from the bitten extremity, as significant swelling may develop 2, 1
• Apply antibiotic ointment and cover with a clean occlusive dressing to improve healing and reduce infection risk 2, 1

Pain Management

• Use over-the-counter acetaminophen or NSAIDs for pain control 1
• Apply topical lidocaine 5% if the skin is intact for additional pain relief 3, 1
• Oral antihistamines can reduce itching and associated swelling 1

Understanding Brown Recluse Envenomation

Brown recluse spider bites can cause painful ulcerated wounds that progress over days to weeks, sometimes associated with hemolysis and rhabdomyolysis 1. The bite often goes unnoticed initially, and diagnosis may be delayed for 4-6 hours or longer 4. The severity ranges from mild erythema to severe necrosis, with rare systemic reactions (loxoscelism) 5, 6.

Critical Pitfall: When NOT to Use Antibiotics

Universal prophylaxis with antibiotics is not recommended for bite wounds 7, 1. Large swelling occurring in the first 24-48 hours is caused by venom-induced inflammatory response and mediator release, not infection 3, 1.

When Antibiotics ARE Indicated

Antibiotics should only be used when there are clear signs of secondary bacterial infection 1:

• Progressive erythema extending beyond the initial bite site 3
• Purulent discharge from the wound 3
• Systemic signs of infection such as fever or elevated white blood cell count 3

For confirmed secondary bacterial infection, use trimethoprim-sulfamethoxazole or doxycycline as first-line oral therapy to cover MRSA 1. Alternative options include clindamycin if local resistance patterns permit 1.

Surgical Management

• Surgical excision should be delayed and is indicated only for lesions that have stabilized and are no longer enlarging 6
• Early surgical debridement is contraindicated as it may worsen tissue injury 6
• The wound may take weeks to months to stabilize before surgical intervention is appropriate 8, 6

Systemic Treatment Considerations

• Steroids are indicated for bites associated with severe skin lesions, loxoscelism, or in small children 6
• Dapsone should only be used in adult patients with necrotic arachnidism who have been screened for glucose-6-phosphate dehydrogenase (G6PD) deficiency 6
• Topical nitroglycerin may decrease enlargement of necrotic skin ulcers 6
• Patients who develop systemic symptoms (difficulty breathing, muscle rigidity, dizziness, confusion) require immediate hospitalization 1

Advanced Therapy for Non-Healing Wounds

Hyperbaric oxygen therapy (HBOT) should be considered for chronic, non-healing brown recluse spider bite wounds that have failed other therapies, even months after the initial bite 8, 4. In case series, HBOT at 2 ATA with 100% oxygen resulted in complete wound healing without need for surgical intervention after 13-31 daily sessions 8.

What NOT to Do

• Do not apply suction to the bite site—it is ineffective and potentially harmful 2, 1
• Do not apply tourniquets or pressure immobilization bandages, as they may worsen tissue injury 2, 1
• Do not perform early surgical excision before the wound has stabilized 6
• Do not assume antibiotics are needed for swelling—this is typically inflammatory, not infectious 3, 1

When to Seek Urgent Medical Care

• Pain extends beyond the bite site or becomes severe 2, 1
• Pain is not controlled by over-the-counter medications 2, 1
• An open wound develops or progressively enlarges 2, 1
• Signs of infection appear (progressive erythema, purulent discharge, fever) 3, 1
• Systemic symptoms develop (difficulty breathing, muscle rigidity, dizziness, confusion, signs of hemolysis) 1

Follow-Up Care

• Most patients with local symptoms only will recover within 24-48 hours, though brown recluse bites may progress over days to weeks 2, 1
• Continue pain management with over-the-counter medications as needed for several days 2, 1
• Follow-up within 24 hours by phone or office visit is advised 1
• Monitor closely for wound progression and development of necrosis over the subsequent weeks 6