What is the appropriate management for a five‑year‑old child weighing about 18–20 kg with an unknown spider bite?

Management of Spider Bite in a Five-Year-Old Child

For a 5-year-old child (18-20 kg) with an unknown spider bite, immediately irrigate the wound thoroughly with water, apply ice with a barrier, elevate the affected area, and use oral antihistamines plus acetaminophen or NSAIDs for symptom control—antibiotics are NOT indicated unless clear signs of secondary bacterial infection develop. 1

Immediate Assessment for Life-Threatening Conditions

First, rapidly assess for systemic symptoms that require emergency intervention:

• Check for anaphylaxis signs: difficulty breathing, bronchospasm, laryngospasm, dizziness, confusion, muscle rigidity, syncope, or hypotension—if present, administer epinephrine 0.01 mg/kg (maximum 0.3 mg) intramuscularly in the anterolateral thigh immediately 2
• Assess for angioedema: rapidly progressive swelling involving face, lips, tongue, or throat requires emergency intervention 1
• Evaluate pain severity: severe pain extending beyond the bite site or uncontrolled by over-the-counter medications warrants urgent medical evaluation 1

Initial Wound Care and Symptomatic Management

Perform these steps in sequence:

1. Wound irrigation: Thoroughly irrigate with copious warm or room temperature water until no foreign matter remains 1, 3

2. Remove constricting objects: Immediately remove rings, bracelets, or tight clothing from the affected area before swelling progresses 1, 3

3. Elevation: Elevate the affected body part to accelerate healing and reduce swelling 1

4. Cold therapy: Apply ice with a clean barrier between ice and skin for local pain relief 1, 3

5. Wound dressing: Apply antibiotic ointment and cover with clean occlusive dressing to improve healing and reduce infection risk 1

6. Pain management:

   • Oral acetaminophen (15 mg/kg/dose every 4-6 hours) or ibuprofen (10 mg/kg/dose every 6-8 hours) 1, 3
   • Topical lidocaine 5% if skin is intact 1

7. Antihistamines: Oral antihistamines (diphenhydramine 1 mg/kg/dose every 6 hours, maximum 50 mg) to reduce itching and swelling 2, 1

Critical Pitfall: When NOT to Use Antibiotics

The most common error is prescribing antibiotics unnecessarily. Large swelling occurring in the first 24-48 hours is caused by allergic inflammation, NOT infection, and does not require antibiotic therapy 2. Universal prophylaxis with antibiotics is not recommended for bite wounds 1.

Only prescribe antibiotics if clear signs of secondary bacterial infection develop:

• Progressive erythema extending beyond the initial bite site 1
• Purulent discharge 1
• Systemic signs such as fever or elevated white blood cell count 1

If secondary infection is confirmed, first-line oral therapy includes:

• Trimethoprim-sulfamethoxazole (8-10 mg/kg/day of TMP component divided twice daily) OR
• Doxycycline (if ≥8 years old: 2-4 mg/kg/day divided twice daily, maximum 200 mg/day) 1

When to Consider Corticosteroids

For severe large local reactions with extensive swelling, a short course of oral corticosteroids may be considered, though controlled studies are lacking 2, 1. Prednisone 1-2 mg/kg/day (maximum 60 mg) for 3-5 days can limit swelling if started within the first 24-48 hours 2.

What NOT to Do

These interventions are ineffective or harmful:

• Do NOT apply suction to the bite site—it is ineffective and potentially harmful 1, 3
• Do NOT apply tourniquets or pressure immobilization bandages—they may worsen tissue injury 1, 3
• Do NOT close infected wounds 2, 1
• Do NOT delay medical care when systemic symptoms are present 1

Follow-Up and Monitoring

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

Special Considerations for Brown Recluse Bites

If brown recluse spider bite is suspected (painful ulcerated wound progressing over days):

• Primary treatment remains rest, ice compresses, and supportive care 1, 4
• Surgical debridement should be delayed for several weeks, not performed acutely 4
• Monitor for systemic complications including hemolytic anemia (can occur early at 2 days or late at 7 days post-bite), rhabdomyolysis, and acute renal failure—these occur in up to 50%, 27%, and 12% of hospitalized pediatric cases respectively 5, 6
• Children with brown recluse bites who develop fever, jaundice, or signs of hemolysis require immediate medical evaluation 5, 6