Jellyfish sting

A jellyfish sting is a contact injury to the skin and mucous membranes caused by the activation of stinging capsules, which release hollow threads containing toxins. The toxins of different jellyfish species vary, but the general principle is the same: first, stop further capsule release and reduce pain. The most important steps on shore are proper rinsing and thermal analgesia in hot water, as well as careful removal of the tentacles. Incorrect "folk" methods such as urine, alcohol, ammonia, and fresh water can increase toxin release and pain. [1]

Different species require different approaches. For box jellyfish in tropical Australia, the priority is to quickly and permanently soak the sting site in vinegar, as it specifically blocks the remaining capsules in these species. For Mediterranean scyphoid jellyfish and the Portuguese man-of-war, vinegar should not be used, as it can enhance the activation of the capsules. Seawater and heat are used instead. These differences have been confirmed by experiments and clinical observations. [2]

Hot water, approximately 43 to 45 degrees Celsius, reduces pain and likely partially inactivates the heat-labile proteins in the venom. This simple step has proven effective for numerous species, especially outside the tropics. An important clarification: "hot, but not scalding," and it's best to use prolonged immersion or a continuous shower. [3]

Even when the skin hurts the most, it's important to take a broader view: some box jellyfish stings can cause systemic effects, including Irukandji syndrome, which can cause elevated blood pressure, back and chest pain, anxiety, and sweating. These conditions require medical supervision and sometimes the administration of an antidote. [4]

Code according to ICD-10 and ICD-11

In the International Classification of Diseases, Tenth Revision, injuries from contact with jellyfish are classified as toxic effects of contact with venomous animals. The basic code is T63.6 "Toxic effect of contact with other venomous marine animals," with additional details for jellyfish: T63.62 and details based on the circumstances of the event, such as T63.621A for accidental contact during initial presentation. The external cause and severity are added if necessary. [5]

The International Classification of Diseases, Eleventh Revision, uses a combination of codes for the harmful effects of animal poisons and toxins, as well as codes for external causes. The "harmful effects or effects of harmful substances" branch includes a post-coordination clause specifying "contact with other marine animals," as well as expanders for marine toxins. For practice, it is important to record the species, region, and circumstances, as this impacts first aid and subsequent management. [6]

Table 1. Examples of coding of clinical situations

Situation	ICD-10 (example)	Comment	ICD-11 (example)	Comment
Jellyfish sting on the forearm, initial treatment	T63.621A	Accidental contact, primary	NE61 + "Contact with other marine animals" expander	Post-coordination by substance and cause
Multiple jellyfish stings on a swimmer, return visit	T63.62 with the clarification "repeat appeal"	Episode details	NE61 + external cause code	Specify the type of event and location
Severe reaction after box jellyfish (suspected Irukandji syndrome)	T63.62 + complication codes	Associated codes for systemic manifestations	NE61 + complication codes	Post-coordination of systemic effects is possible
Contact with the Portuguese man-of-war	T63.62 or T63.69 if the view is not available	There are options	NE61 + "contact with other marine animals"	Specify the type if known

Epidemiology

Tens of millions of people experience jellyfish stings every year. Marine toxicologists estimate that approximately 150 million people worldwide are exposed to jellyfish stings annually, and outbreaks of mass strandings in certain regions place significant strains on emergency services and healthcare. In the Mediterranean, the most common species is Pelagia noctiluca, which is not fatal but creates a significant burden. [7]

On the beaches of Spain and Catalonia, jellyfish stings account for a large proportion of all calls to lifeguards: various observation series show rates of around 60 percent or higher, with seasonal peaks. In recent years, long data series have been published confirming the predominance of such injuries in the structure of beach incidents. [8]

Portuguese man-of-war periodically drifts into the Atlantic and even the Mediterranean, leading to localized outbreaks and rare severe cases. These drifts are associated with wind and current conditions and require prompt warnings for vacationers. [9]

The incidence of chemical contact eye injuries and systemic reactions is low compared to skin lesions, but they necessitate clear evacuation routes and observation. Isolated cases of severe systemic effects have been described for box jellyfish and require preparedness for resuscitation measures. [10]

Reasons

The immediate cause is mechanical irritation of the stinging cells when the skin or mucous membranes come into contact with the tentacles. Triggering factors include waves, rubbing against clothing, attempting to shake off the tentacles with your hand, and repeated contact with fresh water or alcohol, which activates the remaining capsules. Proper removal technique reduces the venom dose. [11]

The risk of contact is higher during storm surges, mass jellyfish strandings, and the presence of detached tentacles in the water. Even dried tentacles on the shore can "shoot" when wet. This is important to explain to children and tourists. [12]

A separate cause of severe outcomes is the specific toxicity of box jellyfish and siphonophores, such as the Portuguese man-of-war. Their toxins can cause severe pain, hypertension, arrhythmia, and, in rare patients, life-threatening reactions. [13]

Finally, improper self-care is often a contributing factor. Vinegar applied to the wrong species, ammonia, fresh water, alcohol, and urine all increase the release of poison and worsen symptoms. [14]

Risk factors

Individual risk factors include childhood, thin skin, allergies, and previous severe reactions to stings. These groups are more likely to require observation, even with seemingly "common" burns. [15]

Environmental risk factors include stormy weather, onshore winds, and warm periods with plankton blooms, when the chances of encountering jellyfish increase. Rescue services typically increase their awareness during these times. [16]

Multiple exposures, large areas of exposure, facial and eye involvement, and exposure to box jellyfish in areas with box jellyfish increase the risk of severe illness. It's important for tourists to understand in advance what species are expected at their destination. [17]

Timing is critical: a slow or improper initiation of first aid increases the depth and duration of pain. Inappropriate fluids and scraping movements can trigger the remaining capsules and increase the dose. [18]

Pathogenesis

The stinging capsule is a miniature, high-pressure "catapult" that fires a filament of barbs and toxins upon mechanical or chemical stimulation. The release is instantaneous, so physical destruction of the tentacles without proper cleaning often worsens the situation. A linear, "whip-like" erythema and edema develop on the skin. [19]

Toxins consist of proteins and peptides, many of which are heat-labile, which partially explains the analgesic effect of hot water. The literature describes pore-forming proteins that affect membranes, as well as components that trigger inflammation and pain. [20]

When stung by box jellyfish, systemic effects of toxins can occur, leading to the development of so-called Irukandji syndrome: after 30 to 120 minutes, generalized pain, sweating, anxiety, tachycardia, and hypertension appear, sometimes with damage to the heart and lungs. These conditions require medical supervision. [21]

In the Portuguese man-of-war, toxins cause severe local pain and sometimes systemic effects, but fatalities are rare. However, high exposure and associated illnesses increase the risk of complications. [22]

Symptoms

Local manifestations include burning pain, erythema, and swelling with characteristic linear tentacle marks, often with blisters. The pain can be very intense during the first minutes and hours and subsides with appropriate thermal analgesia. [23]

Systemic symptoms include nausea, vomiting, dizziness, headache, weakness, rapid heartbeat, and anxiety. In Irukandji syndrome, generalized pain and increased blood pressure develop after a brief "lucid pause." [24]

Eye lesions are accompanied by severe pain, lacrimation, photophobia, and decreased vision. Any contact of the tentacles with the eye requires immediate irrigation and examination by an ophthalmologist, as corneal erosions are possible. [25]

Sensitive individuals may experience severe allergic reactions, including anaphylaxis, which can include shortness of breath, swelling of the lips and eyelids, hoarseness, and a drop in blood pressure. These conditions require immediate medical attention.

Classification, forms and stages

Depending on the type of causative agent, a distinction is made between box jellyfish, scyphozoans, and siphonophores. This is important for choosing first aid: vinegar is indicated for box jellyfish in the tropics, but is contraindicated for most Mediterranean scyphozoans and the Portuguese man-of-war. [26]

Severity is classified as mild localized reactions, moderate reactions with severe pain and blisters, and severe forms with systemic manifestations or eye damage. Severity criteria help determine the need for observation and evacuation. [27]

The disease progression phases are divided into an acute phase of pain and inflammation, a subacute phase with a decrease in pain and itching, and a late phase with the risk of hyperpigmentation and scarring. Each phase has its own care objectives. [28]

Special protocols are in place for potentially dangerous species, including the administration of an antidote for box jellyfish and resuscitation in the event of cardiac arrest. These protocols are used in endemic regions. [29]

Table 2. Types and first aid

Group	Examples	What not to do	What to do first
Box jellyfish (tropical Australia)	Chironex fleckeri, Carukia barnesi	Fresh water, ammonia, alcohol	First vinegar for about 30 seconds, then remove the tentacles and hot water
Scyphomedusae (Mediterranean)	Pelagia noctiluca	Vinegar	Sea water, careful removal of tentacles, hot water
Siphonophores	Portuguese man-of-war	Vinegar	Sea water, tentacle removal, hot water

Complications and consequences

Skin complications include long-term pain, secondary infection, hyperpigmentation, and scarring, especially with delayed or improper initial treatment. Modern atraumatic dressings and care reduce these risks. [30]

Eye lesions are dangerous due to persistent erosions and corneal clouding, requiring early irrigation and ophthalmological observation. Timely treatment improves the vision prognosis. [31]

Systemic complications of box jellyfish include Irukandji syndrome, with cardiovascular complications and pain. In severe cases, heart and lung damage may occur, requiring hospitalization. [32]

Severe reactions to the Portuguese man-of-war have been rarely reported, including shock in susceptible individuals; overall, fatalities are rare, but caution is always necessary.[33]

Table 3. Frequent complications by organ

System	Complications
Leather	Inflammation, infection, hyperpigmentation, scarring
Eyes	Erosions, keratitis, decreased vision
Cardiovascular	Tachycardia, arterial hypertension, chest pain
Respiratory	Bronchospasm, shortness of breath
Nervous	Severe pain, anxiety, headache

When to see a doctor

Immediately - for any eye damage, widespread burns, severe pain, in children, pregnant women and the elderly, as well as signs of a systemic reaction: shortness of breath, weakness, dizziness, chest pain or a significant increase in blood pressure. In regions endemic for box jellyfish, the threshold for seeking medical attention is especially low. [34]

If pain does not subside after proper thermal analgesia and removal of the tentacles, or if blisters and signs of infection appear, an in-person evaluation is required. Increasing itching and scratching increase the risk of complications. [35]

After potential exposure to box jellyfish or if symptoms resembling Irukandji syndrome occur, observation in a medical facility is necessary due to the risk of delayed complications. This also applies to patients with underlying heart disease. [36]

If you lose consciousness, have trouble breathing, or show signs of anaphylaxis, call 911 and begin basic cardiopulmonary resuscitation (CPR) until emergency services arrive. [37]

Diagnostics

The first step is proper first aid. On shore or at home, stop the capsules from further activation: use seawater, carefully remove the tentacles with tweezers or wearing gloves, then immerse the affected area in hot water. Do not use fresh water, alcohol, ammonia, or urine. [38]

Next comes the clinical assessment. The doctor will determine the type of water, the approximate species of jellyfish, the area of the lesion, the presence of linear marks, blisters, or necrosis, as well as signs of a systemic reaction. If box jellyfish are suspected, hemodynamics and pain are assessed using scales. [39]

Instrumental and laboratory diagnostics are indicated based on clinical findings. In case of eye damage, a slit-lamp examination, fluorescein test, and intraocular pressure assessment are mandatory; in cases of severe pain, cycloplegics may be prescribed by a physician. In case of systemic symptoms, an electrocardiogram, oxygen saturation, and key biochemical parameters are monitored. [40]

Inpatient observation is considered for severe pain, large lesions, children, and suspected Irukandji syndrome. The decision regarding pain management, fluid therapy, and antiallergic support is made on an individual basis. [41]

Table 4. Minimum diagnostics by scenarios

Scenario	Priority actions	What to evaluate	What's next?
Leather, not heavy	Sea water, tentacle removal, hot water	Area, pain, blisters	Home care and monitoring
Eyes	Long-term irrigation, lens removal	Slit lamp, test, pressure	Treatment by an ophthalmologist
Systemic symptoms	Observation, monitoring	Blood pressure, pulse, ECG, saturation	Hospitalization according to indications

Differential diagnosis

Jellyfish stings are distinguished from hydroid irritations, sea anemone stings, and coral stings: jellyfish stings typically produce linear marks, pain, and a rapid response to hot water. Coral stings often present with abrasion and a delayed inflammatory response. [42]

Allergic dermatoses after swimming sometimes mask mild stings; a history of contact and the "weave" geometry of the stripes suggest jellyfish. If an unexplained rash develops after swimming, it's important to rule out parasitic dermatitis. [43]

Irukandji syndrome is differentiated from acute cardiovascular events and anxiety-panic attacks. Clues include the association with bathing, the delayed onset of systemic symptoms, and the combination of generalized pain, sweating, and arterial hypertension. [44]

Eye lesions are differentiated from photokeratitis and mechanical erosions. A history of contact with the tentacles and linear marks on the eyelid skin help establish a correct diagnosis. [45]

Treatment

Once on shore, the first step is to cease contact and reduce the venom dose: remove the tentacles with tweezers, a glove, or a cloth and rinse the affected area with seawater to remove loose capsules. The area is then immersed in hot water at approximately 43 to 45 degrees Celsius for 20 to 45 minutes, or longer, until noticeable pain relief is achieved. This treatment reduces pain and likely partially inactivates the protein components of the venom. [46]

In tropical Australia, if a box jellyfish is suspected, vinegar is poured over the affected area for approximately 30 seconds before removing the tentacles to block the release of any remaining capsules, specifically in these species. After this, the same procedure is followed: removing the tentacles and applying hot water. If circulation stops, CPR is initiated and an antidote is administered according to regional protocols. [47]

Vinegar is not used for Mediterranean scyphozoans and the Portuguese man-of-war, as it causes capsule discharge and increases pain. In these regions, first aid standards include rinsing with seawater, careful removal of tentacles, and hot water. Vinegar has been shown to have adverse effects on Pelagia noctiluca in laboratory and field studies. [48]

After initial treatment, symptomatic therapy is prescribed. Mild moisturizers are used locally, and, if prescribed by a doctor, low-potency corticosteroid creams can be used for a short course to reduce inflammation and itching after epithelialization. Oral antihistamines relieve itching but are not a substitute for first aid. Examination is necessary for blisters, signs of infection, and severe pain. [49]

Pain relief is administered in stages: nonsteroidal anti-inflammatory drugs (NSAIDs) and, if necessary, additional analgesics. The duration of immersion in hot water is adjusted based on the desired effect. If immersion is not possible, a hot shower or heating pads are used, taking care not to cause a thermal burn. [50]

For the eyes, the algorithm is strict: immediate irrigation with sterile solution or clean water, removal of contact lenses, followed by a slit-lamp examination, fluorescein test, and intraocular pressure assessment. As prescribed by an ophthalmologist, antibiotic drops, a cycloplegic for pain relief, and preservative-free moisturizing drops are used. Any "home" drops without an examination are contraindicated. [51]

In case of systemic symptoms, blood pressure, pulse, and oxygen saturation are monitored, and infusions and pain support are administered if necessary. Irukandji syndrome is managed in a hospital setting with hemodynamic monitoring; therapy includes pain relief, possibly the use of magnesium, and treatment of complications as indicated. [52]

What you should definitely avoid: do not pour fresh water, alcohol, or ammonia on the skin; do not use urine; do not rub or scrape the skin with a card if the capsules are not yet inactivated. These actions increase the likelihood of additional venom release and intensify the pain. Do not apply ice directly to the skin for long periods of time—cold is ineffective compared to hot water and can worsen discomfort. [53]

In questionable cases, local solutions recommended by regional protocols are used. For example, some guidelines allow for specialized solutions to induce capsule inactivation, but immediate hot water and proper mechanical decontamination always take precedence. If there is any doubt about the type of jellyfish, it is best not to use vinegar until consulting with regional rescuers. [54]

For severe skin burns with blisters, atraumatic dressings are chosen to support moist healing and control infection. A follow-up examination after 24 to 48 hours helps promptly adjust care and prevent further damage. Rehabilitation includes skin care and scratch prevention. [55]

Table 5. Dos and Don'ts for a Jellyfish Sting

Action	Yes or no	Comment
Sea water for rinsing	Yes	Washes away loose capsules without causing discharge
Hot water is approximately 43 to 45 degrees Celsius	Yes	Reduces pain and probably partially inactivates toxins
Vinegar for box jellyfish in the tropics	Yes	Inactivates capsules of these species
Vinegar for Pelagia noctiluca and Portuguese man-of-war	No	Provokes a discharge and increases pain
Fresh water, alcohol, ammonia, urine	No	Increases the release of poison and irritation

Table 6. Pain relief and care

Step	The essence	Target
Thermal analgesia	Hot water until relief	Rapid pain relief
Oral analgesics	Up the steps	Pain management at home
Local therapy	Short course of low-potency corticosteroids as prescribed	Reduces inflammation and itching
Bandages	Atraumatic coatings	Moist healing, infection prevention

Table 7. Special scenarios

Scenario	What is important	Tactics
Irukandji syndrome	Delayed systemic symptoms	Hospitalization and monitoring
Eye damage	Risk of corneal erosion	Irrigation, ophthalmologist
Massive jellyfish release	Many victims	Hot water, sorting, information
Children and the elderly	Higher risk of complications	Low threshold for examination by a doctor

Prevention

Plan your swim according to lifeguard warnings, information boards, and local news about jellyfish strandings. After a storm and when winds blow toward the shore, the risk of contact increases. It's best to choose beaches with patrol posts and shelters. [56]

Use protective gear: a wetsuit, swimming leggings, and protective clothing for children. Do not touch jellyfish or tentacle fragments either in the water or on the shore—even dried fragments can sting. [57]

Keep tweezers handy and know the local protocol: in the Australian tropics, vinegar for box jellyfish; in the Mediterranean, only seawater and hot water. This will buy you precious minutes until help arrives. [58]

Teach children to call an adult immediately after contact and not to rub the skin. Explain why it's not okay to "experiment" with home remedies and why hot water is the primary and safest measure. [59]

Forecast

In most cases, with proper first aid, the pain subsides within 20 to 45 minutes, and the skin heals without leaving a mark in the next few days. Hot water and gentle removal of the tentacles are the key to rapid relief. [60]

In cases of eye damage, the outcome depends on the speed of irrigation and early examination by an ophthalmologist. Delay increases the risk of erosions and vision loss. [61]

Systemic reactions, including Irukandji syndrome, require observation and sometimes intensive care, but with prompt management, patients usually make a full recovery. In endemic areas, knowledge of the signs and routing is lifesaving. [62]

Rare severe outcomes from Portuguese man-of-war are associated with massive contact and associated factors. Prevention and proper first aid minimize risks. [63]

FAQ

Should vinegar be used for any jellyfish sting
? No. Vinegar is used in tropical Australia for box jellyfish. Vinegar is contraindicated for Pelagia noctiluca in the Mediterranean and for the Portuguese man-of-war – rinse with seawater and use hot water. [64]

Will ice help?
Cold water is less effective at relieving pain than hot water and can increase discomfort. Opt for hot water immersion or a temperature-controlled hot shower. [65]

Why fresh water is not recommended:
Fresh water, alcohol, ammonia, and urine trigger the discharge of remaining capsules and increase pain. Sea water and mechanical removal of the tentacles are suitable. [66]

When to go to the hospital
Immediately if there is eye damage, in children and the elderly, if there is a large area of damage, unbearable pain, shortness of breath, dizziness, chest pain, or if Irukandji syndrome is suspected. [67]

Important correction to the original article

The original page recommended ammonia, vinegar, and baking soda, and also mentioned urine as an "aid." All of these remedies can increase venom release in most species and increase pain. The correct approach is seawater, careful removal of the tentacles, followed by hot water, and seeking medical attention if indicated.

Additional tables

Table 8. First aid algorithm by region

Bathing area	Most likely species	Fluids for washing	Additionally
Tropical Australia	Box jellyfish	First vinegar for about 30 seconds, then sea water	Antidote and resuscitation protocol for severe cases
Mediterranean	Pelagia noctiluca	Only sea water	Hot water as a basis for pain relief
Atlantic and Canary Islands	Portuguese man-of-war	Only sea water	Hot water and tentacles removal

Table 9. The benefits and harms of vinegar

Situation	The action of vinegar	Result
Box jellyfish	Blocks remaining capsules	Healthy
Pelagia noctiluca	Causes capsules to discharge	Harmful
Portuguese man-of-war	Increases symptoms	Harmful

Table 10. Mini-cheat sheet for the patient

Step	What to do	What to avoid
Straightaway	Get out of the water, do not rub your skin	Do not use fresh water, alcohol, ammonia, or urine.
Decontamination	Seawater and tentacle removal	Do not scrape without inactivating capsules.
Anesthesia	Hot water until relief	Long-lasting ice
Appeal	Doctor if there are signs of severity	Self-medication with folk remedies