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What Are Jellyfish?

Jellyfish live in the ocean and usually don't bother anyone. They just float around and look weird, sometimes washing up on the beach.

A jellyfish jiggles like gelatin, and some just look like small, clear blobs. But others are bigger and more colorful with a bunch of tentacles that hang down underneath them, kind of like an octopus.

Beware those tentacles! Jellyfish sting so that they can catch and eat other sea creatures. But that sting can be turned on people. Jellyfish can sting if they brush against you when you're swimming in the ocean. You also can get stung if you step on a jellyfish, even a dead one.

Usually, jellyfish stings will hurt, but are not emergencies. Most cause pain, red marks, itching, numbness, or tingling. But a few types of jellyfish (mainly found in Australia, the Philippines, the Indian Ocean, and central Pacific Ocean) are very dangerous, and can make people very sick quickly.

One Jellyfish Sting = Thousands of Tiny Stingers

Jellyfish stings aren't like bee stings when it comes to the stinger. A bee sting leaves behind a single stinger that you can usually see and pull out.

When a jellyfish stings a person, it leaves thousands of very tiny stingers called nematocysts in the skin. These stingers can continue to release jellyfish venom (poison) into the person's body.

What If You Get Stung By a Jellyfish?

If you get stung, take these two steps right away:

  1. Get out of the water.
  2. Tell an adult.

See the lifeguard next, if there's one at your beach. He or she may be able to help and also can warn other swimmers.

It's best to rinse a sting with vinegar. Tentacles left on the skin can be plucked off with a pair of tweezers. Why does vinegar work sometimes? Vinegar is a weak acid. For some kinds of jellyfish stings (especially from dangerous types like box jellyfish), it might keep the stingers from firing.

Here's what a parent or other adult can do to help you feel better if a jellyfish stings you:

  • Rinse the area with vinegar. (Not cool fresh water or seawater, which could make it worse.)
  • Avoid rubbing the area, which also can make things worse.
  • Use tweezers to pull off any tentacles still on your skin. Do not scrape a sting with a plastic card or anything else.
  • Do not put ice or ice packs on a sting. A hot (but not too hot) shower or soak may help with the pain.
  • Check with your doctor. Using certain creams or pain relievers may help you feel better.

Someone needs to call for an ambulance right away if a person who's been stung:

  • has trouble breathing or swallowing
  • has a swollen tongue or lips, or a change in voice
  • has bad pain or feels generally unwell
  • feels nauseated or is vomiting
  • is dizzy or has a headache
  • has muscle spasms
  • has stings over a large part of the body
  • was stung in the eye or mouth
  • may have been stung by a very dangerous type of jellyfish

Avoiding Jellyfish Stings

Swim only at guarded beaches, where you're more likely to get a warning about jellyfish from lifeguards. They might post a sign or fly a warning flag. Some beaches fly a purple warning flag whenever there's "dangerous marine life" in the water.

Also, remind your mom or dad to keep a small container of vinegar and a pair of tweezers in their beach bag.

Reviewed by: Larissa Hirsch, MD
Date Reviewed: Mar 21, 2017

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