What is the treatment for a sea urchin bite?

Treatment of Sea Urchin Injuries

Immediately immerse the affected area in hot water (40-45°C/104-113°F) for 30-90 minutes to inactivate heat-labile toxins and provide pain relief, followed by complete spine removal by a physician under appropriate imaging guidance to prevent long-term complications. 1

Immediate First Aid Management

Hot Water Immersion

• Apply hot water immersion as soon as possible after injury to inactivate pro-inflammatory compounds and venom, using water heated to approximately 40-45°C (104-113°F) for 30-90 minutes 1, 2
• This is the most critical initial step, as it denatures heat-labile toxins and provides significant pain relief 1
• Ensure water temperature does not cause thermal burns by testing before application 1

Wound Cleansing

• Thoroughly cleanse and irrigate the wound with copious amounts of warm or room temperature potable water to remove superficial debris 3
• Sterile normal saline is preferred for irrigation; avoid iodine or antibiotic-containing solutions 3

Definitive Medical Management

Spine Removal Strategy

• All embedded spines should be extracted by a physician rather than attempting self-removal, as improper extraction attempts can worsen the inflammatory response 1, 4
• Obtain imaging (X-ray, ultrasound, or CT) to determine the depth and location of retained spines, particularly for injuries near joints or deep structures 1
• Superficially retained spines trigger granulomatous inflammatory responses, while deeply retained spines near joints can cause sea urchin arthritis, inflammatory tenosynovitis, and other delayed complications 1, 5

Wound Care

• After spine removal, cover the wound with antibiotic ointment or cream and a clean occlusive dressing to promote healing and reduce infection risk 3
• Do not close puncture wounds from sea urchin spines 3

Adjunctive Measures

Tetanus Prophylaxis

• Verify tetanus immunization status and administer tetanus toxoid (0.5 mL intramuscularly) if outdated or unknown 3

Elevation and Monitoring

• Elevate the injured extremity to reduce swelling and accelerate healing 3
• Monitor for signs of infection, systemic toxicity, or delayed hypersensitivity reactions over the following days to weeks 2, 6

Common Pitfalls to Avoid

• Do not attempt aggressive spine removal at the scene, as this increases tissue damage and inflammatory response 4
• Do not apply ice or cold therapy, as heat is the appropriate modality for marine envenomations 3
• Do not assume superficial injuries are benign—even small retained spines can cause granuloma formation, chronic pain, and joint complications if not properly extracted 1, 5
• Do not delay medical evaluation for injuries near joints or deep structures, as these require imaging and specialist consultation to prevent arthritis and tenosynovitis 1

Follow-Up Considerations

• Arrange follow-up within 24-48 hours to assess for infection, retained foreign bodies, or developing complications 3
• Watch for delayed hypersensitivity reactions, which can occur 10+ days after injury and manifest as pruritic, erythematous eruptions 6
• If granulomas develop, surgical excision of both spines and granulomatous tissue may be necessary for symptom resolution 5