Jellyfish stings are fairly common problems for people swimming, wading or diving in oceans. The long tentacles trailing from the jellyfish can inject venom from thousands of microscopic barbed stingers.

Most often jellyfish stings cause instant pain and inflamed marks on the skin. Some stings may cause more whole-body (systemic) illness. And in rare cases they’re life-threatening.

Most jellyfish stings get better over a few days or weeks with home treatment. Severe reactions likely need emergency medical care.

Symptoms of jellyfish stings include:

Severe jellyfish stings can affect multiple body systems. These reactions may appear rapidly or several hours after the stings. Symptoms of severe jellyfish stings include:

The severity of a reaction depends on:

When to see a doctor

Seek emergency treatment if you have severe symptoms.

See your health care provider if your symptoms worsen or the wound shows symptoms of infection.

Jellyfish stings are caused by brushing against a jellyfish tentacle. Tentacles have thousands of microscopic barbed stingers. Each stinger has a tiny bulb that holds venom and a coiled, sharp-tipped tube.

When you brush against a tentacle, tiny triggers on its surface release the stingers. The tube pierces the skin and releases venom. It affects the 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

Many types of jellyfish are fairly harmless to humans. Others can cause severe pain and a full-body (systemic) reaction. These jellyfish cause more-serious problems in people:

Conditions that increase the risk of jellyfish stings:

Possible complications of a jellyfish sting include:

The following tips can help you avoid jellyfish stings:

Diagnosing jellyfish stings generally doesn’t require a visit to a health care provider. If you do go, your provider will likely be able to diagnose your injury by looking at it.

Your health care provider may collect samples of the stingers to help guide treatment.

Treatment for jellyfish stings includes first-aid care and medical treatment.

First-aid care

Most jellyfish stings can be treated as follows:

  1. Carefully pluck visible tentacles with a fine tweezers.
  2. Soak the skin in hot water. Use water that’s 110 to 113 F (43 to 45 C). It should feel hot, not scalding. Keep the affected skin immersed or in a hot shower until the pain eases, which might be 20 to 45 minutes.
  3. Apply 0.5% to 1% hydrocortisone cream or ointment twice a day to the affected skin.

Steps to avoid

These actions are unhelpful or unproved:

Medical treatment

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