What is the diagnosis and management for a 9-year-old male with a stable (Stable Vital Signs (VS)) but slightly tachycardic (Tachycardia) condition after a jellyfish sting on the abdomen?

Jellyfish Sting (Envenomation) - Diagnosis and Management

Diagnosis

This is a jellyfish sting (envenomation) presenting with local dermatological manifestations and mild systemic symptoms (tachycardia). 1

Clinical Assessment

• Look for characteristic whip-like linear skin lesions on the abdomen where tentacles made contact 2
• Monitor for systemic symptoms including persistent tachycardia, hypertension, chest/abdominal/back pain, or respiratory distress that could indicate progression to more severe envenomation 3, 2
• Assess pain severity as this guides treatment intensity 1
• Check for any remaining tentacle material on the skin that requires removal 4

Important Caveat

The mild tachycardia warrants close observation, as certain jellyfish species can cause Irukandji syndrome with cardiac manifestations including elevated troponin levels, though this typically presents with more severe systemic symptoms 2. Given stable vital signs otherwise, this likely represents pain-related tachycardia rather than severe envenomation.

Immediate Management

Step 1: Deactivate Nematocysts and Remove Tentacles

Liberally wash the affected area with vinegar (4-6% acetic acid solution) for at least 30 seconds to prevent further envenomation. 1

• If vinegar is unavailable, use a baking soda slurry as an alternative 1
• Remove any visible tentacles by lifting or pulling (avoid direct manual contact) 4
• Rinse with seawater after tentacle removal 4, 5
• Do NOT use fresh water, as this is less effective and may trigger additional nematocyst discharge 1

Step 2: Pain Management

After deactivating nematocysts, immerse the affected area in hot water (as hot as tolerated, ideally 45°C/113°F) for at least 20 minutes or until pain resolves. 1, 4

• Hot water immersion is the most effective treatment for jellyfish-related pain 4
• The child can take a hot shower or the abdomen can be immersed in hot water 1
• If hot water is unavailable, use dry hot packs as the next best option 1
• Dry cold packs are a second-line alternative but are less effective than heat 1
• Topical lidocaine cream (4-15% formulations) may provide additional pain relief 4

What NOT to Do

Do NOT apply pressure immobilization bandages - this causes further venom release from already-fired nematocysts 1

Avoid ineffective treatments including:

• Aluminum sulfate or meat tenderizer 1
• Commercial aerosol products 1
• Papain (papaya enzyme) 1

Disposition and Follow-up

Observation Period

• Monitor vital signs for at least 30-60 minutes after treatment 3
• Watch for progression of tachycardia or development of chest pain, severe abdominal pain, hypertension, or respiratory symptoms 3, 2

Discharge Criteria (if met)

• Pain adequately controlled
• Vital signs normalized (tachycardia resolved)
• No systemic symptoms developing
• Dermatological reaction limited to local area

Discharge Instructions

• Wound care: Keep area clean with soap and water 1
• Monitor for secondary infection over the next few days 3
• Watch for delayed allergic reactions including urticaria, pruritus, or respiratory symptoms 6, 7
• Return immediately if chest pain, severe abdominal pain, difficulty breathing, or worsening symptoms develop 6, 2

When to Admit or Escalate Care

• Persistent or worsening tachycardia despite treatment
• Development of chest pain, severe abdominal/back pain, or hypertension (Irukandji syndrome features) 3, 2
• Signs of anaphylaxis (facial edema, periorbital swelling, respiratory distress, hypotension) 6
• Inadequate pain control with first aid measures 3

Evidence Quality Note

The evidence for jellyfish sting treatment is of very low certainty due to heterogeneity in species, settings, and interventions studied 5, 3. However, the American Heart Association and American Red Cross guidelines provide the best available consensus recommendations based on available data 1.