Jellyfish stings are relatively common problems for people swimming, wading or diving in seawaters. The long tentacles trailing from the jellyfish body can discharge thousands of microscopic barbed stingers that release venom into your skin.
Jellyfish stings can vary greatly in severity. Most often they result in immediate pain and red, irritated marks on the skin. Some jellyfish stings may cause more whole-body (systemic) illness, and in rare cases, jellyfish stings are life-threatening.
Most jellyfish stings get better with home treatment, but severe reactions require emergency medical care.
The severity of reactions to jellyfish stings depend on a number of factors, including the species and size of the jellyfish, the age and size of the person, the duration of exposure, and the area of skin affected. Common signs and symptoms include:
If left untreated the symptoms generally resolve within one to two weeks. Discoloration of the skin may last one to two months.
Severe jellyfish stings can affect multiple body systems (systemic reaction), not just your skin. These reactions may appear rapidly or several hours after a sting. Signs and symptoms of severe jellyfish stings can include:
When to see a doctor
Seek emergency treatment if:
Jellyfish tentacles contain microscopic barbed stingers (nematocysts). Each nematocyst is made up of a tiny bulb that holds venom and a coiled, sharp-tipped tube. The jellyfish uses the venom to protect itself and kill prey.
When something comes in contact with the tentacle — a fish or a human — tiny triggers on the surface of the tentacle release the nematocysts. The sharp tube penetrates the skin and releases the venom, which affects the immediate area of contact and may enter the bloodstream.
Jellyfish that have washed up on a beach may still release venomous stingers if touched.
Types of jellyfish
Older people and children, as well as those in poor health, are more likely to have severe reactions to jellyfish stings.
Conditions that can increase your risk of getting stung by jellyfish include the following:
In most cases, jellyfish stings don't cause long-term complications.
Others who are highly sensitive to jellyfish venom can develop a severe, potentially life-threatening allergic reaction (anaphylaxis) on exposure to jellyfish. A flood of chemicals released by your immune system during anaphylaxis can cause you to go into shock. Your blood pressure drops suddenly, and the narrowing of airways block normal breathing.
Treatments and drugs
Most jellyfish stings can be treated with home remedies intended to deactivate stingers and ease pain.
People experiencing severe or systemic reactions need immediate emergency care that may include:
People who have stings covering a large area or who have experienced severe or systemic reactions are usually observed for at least six to eight hours because of possible delayed reactions.
Other medical treatments
Lifestyle and home remedies
Most jellyfish stings can be treated with relatively simple at-home remedies. Appropriate steps include:
Remedies to avoid
The following tips can help you avoid jellyfish stings:
If you’re stung, leaving the water as calmly as possible, rather than splashing about, may prevent further activation of stingers.
Last Updated: 2011-09-01
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