Spider Bite Treatment
For most spider bites, treatment consists of thorough wound irrigation with water, ice application with a barrier, over-the-counter pain medications (acetaminophen or NSAIDs), antibiotic ointment, and a clean occlusive dressing—antibiotics are NOT routinely indicated unless clear signs of secondary bacterial infection develop. 1, 2
Initial Wound Care
- Irrigate the bite wound thoroughly with copious amounts of warm or room temperature potable water until all foreign matter is removed 1, 2
- Apply antibiotic ointment and cover with a clean occlusive dressing to improve healing and reduce infection risk 1, 2
- Remove rings and any constricting objects from the affected 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 NOT Needed
Swelling in the first 24-48 hours after a spider bite is caused by allergic inflammation and mediator release, NOT infection—do not prescribe antibiotics prophylactically. 1, 2
- Universal prophylaxis with antibiotics is not recommended for bite wounds 2
- Large local reactions with swelling do not require antibiotic therapy unless true infection develops 2
When Antibiotics ARE Indicated
Antibiotics should only be prescribed when clear signs of secondary bacterial infection appear:
- Progressive erythema extending beyond the initial bite site 2
- Purulent discharge from the wound 2
- Systemic signs of infection such as fever or elevated white blood cell count 2
When infection is confirmed or highly suspected, first-line oral therapy includes:
- Trimethoprim-sulfamethoxazole OR doxycycline to cover MRSA 2
- Alternative: Clindamycin if local resistance patterns permit 2
When to Seek Immediate Medical Care
Patients should seek urgent medical attention if any of the following occur:
- Systemic symptoms develop: difficulty breathing, muscle rigidity, dizziness, confusion, bronchospasm, laryngospasm, syncope, or hypotension 2
- Pain extends beyond the bite site or becomes severe 1, 2
- Pain is not controlled by over-the-counter medications 1, 2
- An open wound develops 1, 2
- Rapidly progressive swelling involving the face, lips, tongue, or throat (suggests angioedema) 2
Special Considerations for Venomous Spider Bites
Brown Recluse Spider (Loxosceles)
- Bites can cause painful ulcerated wounds that progress over days to weeks, sometimes associated with hemolysis and rhabdomyolysis 2, 3, 4
- Primary treatment remains rest, ice compresses, and delayed surgical debridement (several weeks after the bite) 2, 3
- Most bites occur early in the morning and are initially painless, progressing to ulcerating dermonecrosis at the bite site 4
Black Widow Spider (Latrodectus)
- Bites produce muscle spasms and rigidity starting at the bite site within 30 minutes to 2 hours 4, 5
- Treatment includes analgesics and benzodiazepines for muscle spasm and severe pain 5
- Antivenom is not widely available in the United States but may be considered for severe, refractory cases 5
What NOT to Do
- Do not apply suction to the bite site—it is ineffective and potentially harmful 1, 2
- Do not apply tourniquets or pressure immobilization bandages—they may worsen tissue injury 1, 2
- Do not close infected wounds 2
- Do not assume antibiotics are needed for swelling around the bite site 1, 2
Follow-Up Care
- Most patients with local symptoms only will 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 either by phone or office visit is advised 2
- Monitor for signs of secondary infection at the bite site 1, 2