Bite of jellyfish: symptoms, consequences, than to treat

, medical expert
Last reviewed: 11.04.2020

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A pleasant vacation at sea, swimming can spoil the bite of jellyfish. These sea dwellers look beautiful in the water thanks to their bell-shaped form, jerking movement through muscle contraction, transparent walls capable of colored luminescence. But near their mouth opening are the blades, equipped with special stinging cells - cnidocytes, which contain the substance for their own protection and hunting for prey. In contact with jellyfish, it falls on the body and burns it.


It is estimated that jellyfish bites a year make up 150 million  [1], and in some parts of the Pacific Ocean, up to 800 daily events are recorded  [2]. Therefore, in addition to being a public health problem, jellyfish also pose a threat to tourism.


Skin contact with nematocysts resembles an injection, and the subsequent inflammation and irritation of the nerves cause pain, swelling and itching, which can lead to skin necrosis with stronger bites (often in Australian chiropedid cubozoans)  [3]. The local effect of the poison is due to the penetration of the filament and the activity of various compounds, such as phospholipase A2  [4], as well as exocytosis of fat cell granules (and, thus, histamine release is possible)  [5]. Nematocyst can also cause potential systemic symptoms - due to toxins entering the general circulation  [6] - including gastrointestinal (mainly Physalia physalis and Pelagiidae spp.), Muscle (Physalia and cubozoans spp.), Cardiac (Physalia and cubozoans spp.), Neurological ( Physalia and cubozoans spp. And allergic manifestations (Pelagiidae and cubozoans spp.). It is reported that jellyfish toxins also include hemolytic and lethal fractions  [7]. Deadly fractions can contain cardiotoxins that can cause ventricular arrhythmias and cardiac arrest, as well as neurotoxins that can cause respiratory failure and respiratory arrest  [8]. Intravascular hemolytic fractions can also cause acute renal failure. The poison of Cnidarians is also immunogenic, capable of inducing an antibody response.

Symptoms of the jellyfish bite

The reaction to the bite of a jellyfish varies, depending on their species and size. Some cnidocytes are spiky threads stuck into the body like a harpoon and let out their poison, others are long or short, licked or confused the victim. 

Jellyfish poisons are made up of powerful protein porins (toxins that pore the cell membrane), neurotoxic peptides, biologically active lipids, and other molecules. [9] Upon contact with human skin or another surface (for example, the cornea), thousands of tootins containing toxins are deposited in the epidermis and dermis, they cause local and systemic damage and can also cause immunological reactions. [10

What does a jellyfish bite look like? The most common symptom of a jellyfish bite is a burn that resembles an allergy. It manifests itself:

  • reddening of the place of contact;
  • the appearance of a rash;
  • soreness;
  • itching, desire to scratch the affected area all the time;
  • upon contact with a large individual, small blisters of the rash may merge into blisters;
  • increased body temperature;
  • vomiting, nausea after extensive contact;
  • sometimes anaphylactic shock.

Very unpleasant feeling, if the jellyfish stung in the eyes. From this appears pain, redness, tearing.

A separate bite syndrome with small, four-cheeked box jellyfish, called Irukandji syndrome, characterized by sweating, anxiety, muscle spasm, severe hypertension, potentially late hypotension and heart failure, is described. [11]

Jellyfish species

Since the boundaries of the modern world are greatly expanded, it is necessary to have an idea not only about the jellyfish that live in our internal seas, but also far beyond them. It is necessary to know how the bites of the inhabitants of the waters to be traveled look like and what they are fraught with.

  • The bite of the cross jellyfish (Gonionemus vertens) - these marine inhabitants can be found in the Pacific Ocean, there is a small population in the Atlantic, western part of it. They got their name because of the orange cross at the top of the transparent dome - the sex glands, along the perimeter of which are tentacles with poison (about 60). Their maximum diameter reaches 40cm.

The largest number of jellyfish, as a rule, appears at the end of summer, at the beginning of autumn, in warm weather. Their poison is designed for small marine life (shrimp, fry) and can not kill a person, but it has a neuro-paralytic property and is perceived as an electric shock. It can cause asthma attacks and even convulsions, which for those in the water can turn into drowning. The bite of G. Vertens causes a burning sensation in the skin, which is accompanied by the rapid appearance of blisters and local edema, after 10-30 minutes by general weakness. There is numbness, as well as pain in the joints of the arms and legs; breathing becomes difficult and may temporarily stop. Sometimes there is a violation of the liver. Acute symptoms last four to five days. [12], [13]

  • The bite of the Black Sea jellyfish - 2 species of relatively large jellyfish are found in the Black Sea: Aurelia and Cornerot (Rhizostoma pulmo). The first is relatively harmless and is able to leave weak marks in the form of light reddening. [14] Lesions can heal for more than ten days. [15] The second reaches a half-meter size and more poisonous. After it, blisters may appear and the temperature may rise, and in some cases the functions of the internal organs may be disturbed. In the Cornerot or blue jellyfish (because of its color), the strestral cells are found only in the oral lobes, representing numerous processes, and are not on the dome, therefore its touch is not dangerous. Hemispherical umbrella, bell-shaped, without tentacles; several edge lobes are present.

Rhizostoma pulmo is moderately poisonous. However, contact with Rhizostoma pulmo can cause erythematous and ulcerative lesions; rare cases of dermatitis are described as mild erythema, disappearing spontaneously after a few hours, even though burns on the skin and especially the lips, sneezing and rhinorrhea, urticaria and systemic symptoms were mentioned  [16]. Recently reported episodes of contact dermatitis, which confirms its toxicity to humans: contact caused immediate skin pain, followed by an erythematous, slightly infiltrated eruption and the formation of vesicles; after topical corticosteroid therapy, the pain disappeared after 36 hours.

Complications and consequences

For how much is a jellyfish bite? Everything is individual and depends on the size of the sea animal and the composition of its poison. So, the poison of the krestovik is eliminated from the body after 4 days, and some of the more dangerous species and 2-3 weeks. There may even be scars on the body.

Is there a real health hazard with a jellyfish bite? Its kind as a sea wasp living in the waters of Thailand, where travelers travel so often from winter, leaves not only scars, but also carries a deadly threat to life, because in some cases leads to cardiac arrest. To prevent this from happening, you must immediately enter the antidote.

Is there any benefit from jellyfish bites? Scientists claim that their poison brings relief to those suffering from rheumatism, relaxes the muscles bound by the disease.

The bite of a jellyfish during pregnancy (many future moms love to spend their last free days by the sea) has the same consequences as for other people.

Treatment of the jellyfish bite

The treatment of a jellyfish bite is aimed at: alleviating the local effects of poison, preventing further discharge of nematocysts and controlling systemic reactions, including shock. In severe cases, the most important step is the stabilization and maintenance of vital functions. 

Oral or local analgesics, 30-second use of homemade vinegar (4–6% acetic acid) can be used to prevent further spread of nematocysts remaining on the skin. [17] Conversely, the use of alcohol, methylated alcohols and fresh water should be avoided, as they can contribute to the release of nematocysts; It is also necessary to avoid dressings with immobilization under pressure, as studies show that it stimulates the additional release of venom from nematocysts. 

Most often, a jellyfish bite does not require special medical care, unless it is a large area of damage, the appearance of a strong allergic reaction with tachycardia, difficulty breathing.

What to do with a jellyfish bite? 

It is still being discussed which method is most suitable for removing tentacles, since these procedures can stimulate the further release of nematocysts  [18]. You need to immediately get to dry land and, without touching the faulty place, sprinkle it with salt water  [19],  [20]and use tweezers to remove the tentacles  [21]. Using, say, a plastic card, a razor or a knife to extract the sting. To do this, objects should be held, pressing to the body at an angle of 30º. Tentacles can also be removed with bare hands, but it is better to immediately wash the rescuer's fingers thoroughly to prevent secondary bites. After removing all tentacles, the wound is washed with warm water, ice can also be applied, as it slows down the diffusion of the poison, thus acting as a painkiller, while the mechanism for alleviating pain from warm objects is still under discussion. Some authors argue that heat can modulate pain receptors, which leads to a reduction in pain.

It has been reported that high doses of intravenous ascorbate reduce pain 10 minutes after administration. Vitamin C is said to be effective against various toxins. [22]

Immobilizing dressings for the jellyfish bite site remains controversial and is considered potentially dangerous  [23], with some not recommending it as a first aid tool. A significant amount of poison can remain in the nematocysts that have not yet been released, which have adhered to the patient's skin, and the pressure of the dressing can stimulate the extrusion of the poison from them. [24]

How to handle a jellyfish bite? Antihistamine ointments and sprays, oral agents will help relieve itching and irritation, after which you can apply a gauze bandage. It is recommended at this time to drink a lot.

Jellyfish bite remedies

From jellyfish burns, you can apply ointments and creams based on corticosteroids: Akriderm, Triderm, Belogent, Celestoderm, etc.

From tablets, you can use the following antihistamines: citrine, edem, diazolin, suprastin. [25]

Research on topical inhibitors as effective measures to prevent jellyfish bites continues and looks promising  [26]. Skin inhibitor cream (Safe Sea®, Nidaria Technology, Zemah, Israel) is already available in many countries of the world, provides protection to swimmers from jellyfish bites. This drug was recently developed as a waterproof sunscreen containing octylmethoxycinnamate and zinc oxide, which allows you to inactivate jellyfish and protect against sunburn. Due to its water-repellent properties, jellyfish find it harder to attach their tentacles to the body, and the chemicals contained in it block the release of venom from stinging cells. But he does not help after the bite of a jellyfish. 

Can I swim after being bitten by a jellyfish?

Depending on the state of health and the condition of the skin, you can decide to swim or not. Slight water does not hurt a minor defeat, and therefore, there is no need to lose a day without water procedures.


It is best to take care of how to avoid being bitten by jellyfish. First, do not go to the sea in the season of their accumulation. In terms of preventive medicine, divers and swimmers in hazardous areas should wear personal protective equipment. They are, in fact, almost completely effective against all jellyfish bites and are usually recommended for all people (tourists, locals and diving enthusiasts). [27] Also avoid contact with them in water and on land. In places equipped for swimming, the influx of jellyfish is monitored, and a purple flag is hung out to indicate danger in the water. Using a lotion designed to protect against burns will prevent dangerous effects.

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