Jellyfish are sea creatures. They have nearly see-through bodies with long, finger-like structures called tentacles. Stinging cells inside the tentacles can hurt you if you come in contact with them. Some stings can cause serious harm. Almost 2000 species of animals found in the ocean are either venomous or poisonous to humans, and many can produce severe illness or fatalities.
This article is for information only. DO NOT use it to treat or manage a jellyfish sting. If you or someone you are with is stung, call your local emergency number (such as 911), or your local poison center can be reached directly by calling the national toll-free Poison Help hotline (1-800-222-1222) from anywhere in the United States.
Types of potentially harmful jellyfish include:
There are also other types of stinging jellyfish.
If you are unfamiliar with an area, be sure to ask local ocean safety staff about the potential for jellyfish stings and other marine hazards. In areas where box jellies may be found, especially at sunset and sunrise, full body coverage with a "stinger suit," hood, gloves, and booties is advised.
Symptoms of stings from different types of jellyfish are:
SEA WASP OR BOX JELLYFISH
For the great majority of bites, stings, or other forms of poisoning, the danger is either drowning after being stung or an allergic reaction to the venom.
Seek medical help right away. Get medical attention right away if pain increases or there are any signs of breathing difficulty or chest pains.
Have this information ready:
Your local poison control center can be reached directly by calling the national toll-free Poison Help hotline (1-800-222-1222) from anywhere in the United States. This national hotline will let you talk to experts in poisoning. They will give you further instructions.
This is a free and confidential service. All local poison control centers in the United States use this national number. You should call if you have any questions about poisoning or poison prevention. It does NOT need to be an emergency. You can call for any reason, 24 hours a day, 7 days a week.
The health care provider will measure and monitor the person's vital signs, including temperature, pulse, breathing rate, and blood pressure. Symptoms will be treated. The person may receive:
Most jellyfish stings improve within hours, but some stings can lead to skin irritation or rashes that last for weeks. Contact your provider if you continue to have itching at the sting site. Topical anti-inflammatory creams may be helpful.
Portuguese man-of-war and sea nettle stings are rarely deadly.
Certain box jellyfish stings can kill a person within minutes. Other box jellyfish stings can lead to death in 4 to 48 hours after a sting due to "Irukandji syndrome." This is a delayed reaction to the sting.
It is important to carefully monitor box jellyfish sting victims for hours after a sting. Seek medical attention right away for any breathing difficulties, chest or abdominal pains, or profuse sweating.
Reviewed By: Jacob L. Heller, MD, MHA, Emergency Medicine, Emeritus, Virginia Mason Medical Center, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.