What are the effects and treatment of a jellyfish sting?

Jellyfish Sting Effects and Treatment

Effects of Jellyfish Stings

Most jellyfish stings in North America cause only local pain and discomfort, but severe systemic reactions including difficulty breathing, shock, and allergic reactions can occur and require immediate emergency care. 1

Local Effects

• Pain and discomfort at the sting site are the most common symptoms 1
• Red, warm, tender skin may develop at the site of envenomation 2
• Erythema and swelling can occur from venom mediators 2, 3

Systemic Effects (Less Common but Serious)

• Allergic reactions including anaphylaxis can occur, though uncommon 1, 4
• Severe systemic symptoms from certain species (e.g., box jellyfish, Irukandji syndrome) can include severe pain, hypertension, and even death 2
• Guillain-Barré syndrome has been associated with jellyfish stings in rare cases 2
• Signs requiring emergency care: difficulty breathing, signs of shock, or severe uncontrolled pain 1

Treatment Algorithm

Step 1: Immediate Assessment and Observation

Observe the victim for systemic reactions and call emergency services immediately for difficulty breathing, signs of shock, or severe pain. 1

• Most severe reactions occur soon after envenomation, though the ideal observation period is unknown 1
• Have epinephrine available for anaphylaxis treatment if signs develop 4

Step 2: Tentacle Removal

Remove any remaining tentacles by gently lifting or pulling while avoiding direct manual contact. 1

• Use tweezers or a similar tool to avoid direct skin contact 5
• Never scrape tentacles, as scraping causes significantly more hemolysis and venom release compared to gentle pulling 1, 5
• Rinse with seawater if mechanical removal is not available, as seawater will not trigger additional nematocyst discharge 1, 5, 6
• Avoid fresh water, alcohol, or methylated spirits, as these massively discharge unfired nematocysts 3, 7

Step 3: Pain Management (Primary Treatment)

After tentacle removal, immerse or irrigate the affected area with hot water at 40°C (104°F) for pain relief—this is the most effective first aid intervention. 1, 5

• Hot water immersion/irrigation shows clear benefit in human studies and systematic reviews compared to cold application, vinegar, meat tenderizer, or no treatment 1
• Ensure water is nonscalding to prevent burns 1
• Continue hot water application as needed for pain control 5

Step 4: Alternative Pain Management

If hot water is unavailable, apply topical lidocaine cream or gel (4%-5% or 10%-15% formulations) for pain control. 1, 5, 8

• Lidocaine inhibits nematocyst discharge and decreases pain from multiple jellyfish species 1, 5
• This is a reasonable alternative when hot water cannot be accessed 1

Critical Pitfalls to Avoid

Do NOT Use These Interventions:

• Scraping motions to remove tentacles—increases hemolysis and venom release 1, 5
• Fresh water for rinsing—triggers massive nematocyst discharge 3, 7
• Alcohol or ethanol—causes increased hemolysis compared to gentle tentacle removal 1
• Ice or cold application—less effective than hot water for pain relief 1
• Pressure immobilization bandaging—may stimulate additional venom discharge 3

Additional Considerations

Vinegar Use (Species-Dependent)

• While vinegar (4%-6% acetic acid) has been traditionally suggested and may prevent further nematocyst discharge in some species, hot water immersion remains the most effective intervention for pain relief based on current evidence 1, 3
• The 2024 American Heart Association guidelines prioritize hot water over vinegar for North American jellyfish species 1

Wound Care

• After initial treatment, the area may be covered with antibiotic ointment and clean dressing if skin breakdown occurs 9, 10
• Antibiotics are not routinely indicated unless secondary infection develops 9

Evidence Quality Note

The evidence for jellyfish sting treatment remains limited with significant heterogeneity between species, but the 2024 American Heart Association guidelines provide the most current and authoritative recommendations prioritizing hot water immersion as the primary pain management strategy 1, 6