What is the treatment for a spider bite?

Treatment for Spider Bites

For non-venomous spider bites, thoroughly irrigate the wound with copious water, apply antibiotic ointment with a clean dressing, use ice for pain relief, and manage pain with over-the-counter acetaminophen or NSAIDs—antibiotics are NOT routinely indicated unless clear signs of secondary bacterial infection develop. 1

Initial Wound Care

• Irrigate the bite wound thoroughly with large volumes of warm or room temperature potable water until all foreign matter is removed 1
• Apply antibiotic ointment and cover with a clean occlusive dressing to improve healing and reduce infection risk 1
• Remove rings and other constricting objects from the bitten extremity immediately, as swelling may occur 1, 2
• Elevate the affected area to accelerate healing and reduce swelling 2

Pain Management

• Apply ice to the bite site with a clean barrier between ice and skin for local pain relief 1, 2
• Use over-the-counter acetaminophen or NSAIDs for pain control 1, 2
• Topical lidocaine 5% can be applied if the skin is intact for additional pain relief 2
• Oral antihistamines can reduce itching and swelling 2

Critical Pitfall: When Antibiotics Are Actually Needed

Swelling in the first 24-48 hours is caused by allergic inflammation and mediator release, NOT infection—do not assume antibiotics are needed. 1, 2

• Universal prophylactic antibiotics are NOT recommended for bite wounds 2
• Antibiotics are only indicated when clear signs of secondary bacterial infection appear:
  • Progressive erythema extending beyond the initial bite site 2
  • Purulent discharge 2
  • Systemic signs such as fever or elevated white blood cell count 2
• If secondary bacterial infection is confirmed, use trimethoprim-sulfamethoxazole or doxycycline as first-line oral therapy to cover MRSA 2
• Alternative options include clindamycin if local resistance patterns permit 2

When to Seek Immediate Medical Care

• Difficulty breathing, bronchospasm, or laryngospasm indicating anaphylaxis 2
• Rapidly progressive swelling involving face, lips, tongue, or throat suggesting angioedema 2
• Muscle rigidity, dizziness, confusion, syncope, or hypotension 2
• Severe pain extending beyond the bite site or uncontrolled by over-the-counter medications 1, 2
• Development of an open wound or signs of infection 1

What NOT to Do

• Do not apply suction to the bite site—this is ineffective and potentially harmful 1, 2
• Do not apply tourniquets or pressure immobilization bandages, as these may worsen tissue injury 1, 2
• Do not close infected wounds 2
• Do not delay medical care when systemic symptoms are present 2

Special Considerations for Venomous Spiders

Brown Recluse Spider Bites (Loxosceles)

• Brown recluse bites can cause painful ulcerated wounds that progress over days to weeks, sometimes with hemolysis and rhabdomyolysis 2, 3
• Primary treatment remains rest, ice compresses, and delayed surgical debridement for several weeks 2, 3
• Recluse spider bites are often overdiagnosed and should be treated supportively 4
• Dapsone may be considered for severe dermonecrosis developing within 72-96 hours 3
• Systemic corticosteroids may be helpful for rare systemic loxoscelism with massive hemolysis 3

Black Widow Spider Bites (Latrodectus)

• Black widow envenomation causes muscle spasm, severe pain, and neuromuscular symptoms rather than marked skin changes 3, 4
• Treat with analgesics and benzodiazepines for muscle cramping and pain 4, 5
• IV opioids combined with benzodiazepines provide effective pain relief, with 55-70% of patients obtaining symptomatic relief 5
• Calcium gluconate is NOT effective for pain relief—96% of patients treated initially with calcium gluconate required additional IV opioids or analgesics 5
• Antivenin significantly shortens symptom duration (mean 9 hours vs 22 hours without antivenin) and reduces hospitalization rates (12% vs 52%) 5
• Antivenin should be considered for severe, refractory cases, though it is not widely available in the United States 4, 5

Follow-Up Care

• Most patients with local symptoms only recover completely within 24-48 hours 1, 2
• Continue pain management with over-the-counter medications as needed for several days 1, 2
• Follow-up within 24 hours by phone or office visit is advised 2
• Monitor for signs of secondary infection requiring prompt medical attention 1