What are jellyfish stings?
Jellyfish have been around for millions of years and live in oceans all over the world. There are many different types of jellyfish. Some just look like small, clear blobs, while others are bigger and more colorful with tentacles hanging beneath them.
It’s the tentacles that sting. Jellyfish sting their prey with them, releasing a venom that paralyzes their targets. Jellyfish don’t go after humans, but someone who swims up against or touches one — or even steps on a dead one — can be stung all the same.
While jellyfish stings are painful, most are not emergencies. Expect pain, red marks, itching, numbness, or tingling with a typical sting.
But stings from some types of jellyfish — such as the box jellyfish (also called sea wasp) — are very dangerous, and can even be deadly. These jellyfish are most often found in Australia, the Philippines, the Indian Ocean, and central Pacific Ocean.
How common are jellyfish stings?
Jellyfish stings are relatively common problems for people swimming, wading or diving in seawaters. Please discuss with your doctor for further information.
What are the symptoms of jellyfish stings?
The common symptoms of jellyfish stings are:
- Burning, prickling, stinging pain
- Red, brown or purplish tracks on the skin — a “print” of the tentacles’ contact with your skin
- Throbbing pain that radiates up a leg or an arm
Severe jellyfish stings can affect multiple body systems. These reactions may appear rapidly or several hours after the stings. Signs and symptoms of severe jellyfish stings include:
- Stomach pain, nausea and vomiting
- Muscle pain or spasms
- Weakness, drowsiness, fainting and confusion
- Difficulty breathing
- Heart problems
The severity of your reaction depends on:
- The type and size of the jellyfish
- Your age, size and health, with severe reactions more likely in children and people in poor health
- How long you were exposed to the stingers
- How much of your skin is affected
There may be some symptoms not listed above. If you have any concerns about a symptom, please consult your doctor.
When should I see my doctor?
If you have any signs or symptoms listed above or have any questions, please consult with your doctor. Everyone’s body acts differently. It is always best to discuss with your doctor what is best for your situation.
What causes jellyfish stings?
Jellyfish tentacles contain microscopic barbed stingers. Each stinger has a tiny bulb that holds venom and a coiled, sharp-tipped tube. The jellyfish uses the venom to protect itself and kill prey.
When you brush against a tentacle, tiny triggers on its surface release the stingers. The tube penetrates the skin and releases venom. It 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.
What increases my risk for jellyfish stings?
There are many risk factors for jellyfish stings, such as:
- Swimming at times when jellyfish appear in large numbers (a jellyfish bloom)
- Swimming or diving in jellyfish areas without protective clothing
- Playing or sunbathing where jellyfish are washed up on the beach
- Swimming in a place known to have many jellyfish
Diagnosis & treatment
The information provided is not a substitute for any medical advice. ALWAYS consult with your doctor for more information.
How are jellyfish stings diagnosed?
You generally won’t need to see your doctor for a jellyfish sting. If you do visit your doctor, he or she will be able to diagnose your injury by looking at it.
Sometimes treatment is based on the type of jellyfish that caused the sting. Your doctor may collect samples of the stingers.
How are jellyfish stings treated?
Treatment for jellyfish includes first-aid care and medical treatment, depending on the type of jellyfish, the severity of the sting and your reaction to it.
Most jellyfish stings can be treated as follows:
- Rinse the area with vinegar.
- Carefully pluck visible tentacles with a fine tweezers.
- Soak the skin in hot water. Use water that’s 43 to 45 C. If a thermometer isn’t available, test the water on an uninjured person’s hand or elbow — it should feel hot, not scalding. Keep the affected skin immersed or in a hot shower for 20 to 45 minutes.
Steps to avoid
These actions are unhelpful or unproved:
- Scraping out stingers
- Rinsing with seawater
- Rinsing with human urine
- Rinsing with fresh water
- Applying meat tenderizer
- Applying alcohol, ethanol or ammonia
- Rubbing with a towel
- Applying pressure bandages
- Emergency care. Someone having a severe reaction to a jellyfish sting may need cardiopulmonary resuscitation (CPR), life support or, if the sting is from a box jellyfish, antivenin medication.
- Oral medicine. A rash or other skin reaction due to delayed hypersensitivity may be treated with oral antihistamines or corticosteroids. You may also be given oral pain medicine.
- Eye flushing. A jellyfish sting occurring on or near an eye requires immediate medical care for pain control and a good eye flushing. You will likely be seen by a doctor specializing in eye care (ophthalmologist).
Lifestyle changes & home remedies
What are some lifestyle changes or home remedies that can help me manage jellyfish stings?
The following lifestyles and home remedies might help you avoid jellyfish stings:
- Look for a sign or warning flag (some beaches fly a purple warning flag when there’s “dangerous marine life” in the water).
- Double check to make sure that you’ve got a small container of vinegar and a pair of tweezers in your beach bag.
If you have any questions, please consult with your doctor to better understand the best solution for you.
Hello Health Group does not provide medical advice, diagnosis or treatment.
Review Date: November 20, 2017 | Last Modified: November 20, 2017
Jellyfish Stings. http://kidshealth.org/en/parents/jellyfish.html. Accessed November 20, 2017.
Jellyfish stings. https://www.mayoclinic.org/diseases-conditions/jellyfish-stings/symptoms-causes/syc-20353284. Accessed November 20, 2017.