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Jellyfish are sea creatures that have a nearly see-through (transparent) body 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.
This is for information only and not for use in the treatment or management of an actual poison exposure. If you have an exposure, you should call your local emergency number (such as 911) or the National Poison Control Center at 1-800-222-1222.
Types of jellyfish include:
Lion's mane (Cyanea capillata)
Portuguese man-of-war (Physalia physalis)
Sea nettle (Chrysaora quinquecirrha), one of the most common jellyfish found along the Atlantic and Gulf coasts
Sea wasp (Chironex fleckeri, Chiropsalmus quadrigatus), also known as box jellyfish, found near the coasts of northern Australia and the Philippines
Note: This list is not all-inclusive.
- Abdominal pain
- Changes in pulse
- Chest pain
- Muscle pain and muscle spasms
- Numbness and weakness
- Pain in the arms or legs
- Raised red spot where stung
- Runny nose and watery eyes
- Swallowing difficulty
Sea wasp or box-jellyfish:
- Breathing difficulty
- Nausea and vomiting
- Severe pain and swelling
- Slow heart beat
- Skin tissue death
Seek immediate medical attention.
If you know for certain that the person has been stung by a Portuguese man-of-war or sea nettle, wash with salt water (ocean water is okay, but make sure you do NOT get sand in the wound). Protect affected area if possible. Soak the area with a solution made of 1/2 vinegar and 1/2 water for about 30 minutes. This helps remove the tentacles. Rinse the area and then re-soak with more 1/2 strength vinegar.
(You may also remove tentacles by applying a paste made of flour or shaving cream and scraping the area with a dull instrument such as a credit card.)
Apply a cream containing a pain-killer, an antihistamine, or a corticosteroid.
Before Calling Emergency
Determine the following information:
- Patient's age, weight, and condition
- Name of the marine animal, if possible
- Time stung
The National Poison Control Center (1-800-222-1222) can be called from anywhere in the United States. This national hotline number 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.
See: Poison control center - emergency number
What to Expect at the Emergency Room
The health care provider will measure and monitor the patient's vital signs, including temperature, pulse, breathing rate, and blood pressure. Symptoms will be treated as appropriate. The patient may receive:
- Antivenin (for sea wasp stings)
- Blood and urine tests
- Breathing assistance
- Fluids through a vein (by IV)
- Medication to treat symptoms
Portuguese man-of-war and sea nettle stings are rarely deadly. Sea wasp stings can be deadly in minutes. The overall mortality rate after box-jellyfish stings may approach 15% to 20% in select locales.
Do not swim in waters known to harbor jellyfish. Ask local inhabitants if it is safe to swim in waters with which you are not familiar.
Simon B, Hern HG Jr. Wound management principles. In: Marx JA, ed. Rosen's Emergency Medicine - Concepts and Clinical Practice. 7th ed. Philadelphia, Pa: Mosby Elsevier; 2009:chap 56.
Isbister GK, Caldicott DG. Trauma and evenomations from marine fauna. In: Tintinalli JE, Kelen GD, Stapczynski JS, Ma OJ, Cline DM, eds. Emergency Medicine: A Comprehensive Study Guide. 6th ed. New York, NY: McGraw-Hill; 2004:chap 196.
Auerbach, PS. Envenomation by Aquatic Invertebrates. In: Auerbach PS, ed. Wilderness Medicine. 6th ed. Philadelphia, Pa: Mosby Elsevier; 2011:chap 80.
- Last reviewed on 10/18/2013
- Jacob L. Heller, MD, MHA, Emergency Medicine, Virginia Mason Medical Center, Seattle, Washington. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
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This page was last updated: May 5, 2014