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Catfish Dive & Safari
Dive Medical questions & answers for common scuba diving conditions and illness provided in conjunction with the doctors at the London Diving Chamber and Midlands Diving Chamber.
All Categories » Animal Hazards » Jellyfish


I am going to Baja California in October and after a nasty sting in the Red Sea by a jellyfish, would like to know more about how to prevent it happening again, and what to do afterwards?


Fear not because at least now you are going to a relatively jelly free part of the world. The Sea of Cortez is not as bad as other parts of the Pacific for this problem. What you always need to do when you are swimming or diving in a new area is ask the locals. They should be able to tell you if there are any jellyfish blooms or a sudden influx of these creatures locally. This can commonly happen after a storm or strong onshore wind.

Now if there are local reports of their presence and you still have to go into the water the best thing to do is prevent yourself from being stung. This is best achieved by wearing a full wetsuit or a suit called a stinger suit. This is made from Lycra, fits snugly and will stop the jelly from stinging you, but only on the non exposed parts of your body.

The way jellyfish feed is by enveloping their prey in their tentacles and paralysing them with "nematocysts". These are tiny bags full of venom that are found on the tentacles, and on contact with a fish or human skin they fire off, releasing the poison into whatever they are in contact with. If this happens to be you or a friend then you need to act quickly.

Get out of the water as soon as you can and have someone help get any tentacles off your skin. They must first of all stop any remaining nematocysts from firing off and the best thing for this is ordinary household vinegar. Pour this over the area affected and on any remaining tentacles. If there is no vinegar handy then there are other fluids you can use, the best of which is urine, which may seem bizarre but has good medical grounding due to its relative warmth and acidity.

Having been doused in whatever liquid try to take off any remaining tentacles with gloved hands so you don't get stings on your fingers.

Now, depending on what sort of jellyfish it was appropriate action needs to be taken. If you were in Eastern Australia where the deadly Box Jellyfish frequents then you need to get some antivenom as soon as possible and go under medical supervision for a while, but fortunately most stings are not deadly, just really painful.

Take a simple analgesic such as ibuprofen and apply some calamine lotion on the affected area twice a day too.

Finally, when you're diving remember to always look up when surfacing after a dive, as this is where most problems happen, and going up headfirst into a Portuguese Man'o'War is not the best way to enjoy Baja.


I got your email address from the BSAC list of approved diving doctors and wondered if you could offer some advice.
While diving in the Atlantic off the coast of La Gomera in the Canary Islands my daughter suffered a jellyfish sting on her face. We treated it immediately with a sting remedy from the chemist called 'After bite'. It looked very red and was quite swollen. After it calmed down we started applying vitamin E cream to try and repair the skin, which was still quite red and chafed looking.

Now, nearly five weeks later it still hasn't disappeared completely and in fact started to hurt again, not only on the site of the sting itself, but also around it and across her chin. It seems very dry and there are darkish marks in a patch where she was stung, which become prominent if she gets a bit cold, e.g after swimming.

I think the jellyfish was called a 'medusa' but I don't know the latin name. Do you think it needs looking at by a doctor? Is it possible that there is something remaining in there that needs to be removed?

I would appreciate any advice you may be able to give.


Interesting one, this. 5 weeks after a jelly sting, to be getting pain and deformity. It must be the result of scarring is all I can assume. It is unlikely that there are any nematocysts still there, but certainly infection is a possibility.

I would try a cream with some antibiotic and steroid, e.g fucibet twice a day for a week. If this doesn't nail it and there's still a problem then you may be better off seeing a dermatologist for a closer look.

From my own experience with a similar beastie called a hydroid, the pain and itchiness can last for a good few weeks.


Yesterday my wife got stung by a jellyfish whilst diving in the waters off Saudi Arabia. We washed the affected area with vinegar and soaked it in hot water. However she still has a lot of pain and no painkiller is working. She took an antihistamine shot. She now has started antibiotics (amoxycillin 875mg, clavulanic acid 125 mg). Please assist us to find the cure and end her pain, as I am suffering too, to see her in such distress. Many thanks for any advice you can offer us.


Jellyfish are stunningly versatile creatures, with over 2000 species living in all the world’s oceans from the surface to the deep sea. They’re clearly not fish, they don’t have recognisable organ systems, they’re over 90% water and unfortunately for us, some have a very effective defence mechanism. Contact with a tentacle causes the discharge of millions of specialised stinging cells called nematocysts, which pierce the hapless victim’s skin before injecting poison to immobilise them. Luckily only a few are deadly, some in fact produce no noticeable effect whatsoever, but best not to play with a jelly just in case. And so to treatment: if there are tentacles still clinging to the skin, these should be doused liberally in vinegar and then lifted off as gently as possible, with tweezers or gloved hands. A judicious coating of flour can aid the removal of particularly adherent tentacles with a blunt knife. Rubbing the wound or saturating it with alcohol, ammonia or urine seems to cause further nematocyst discharge, so avoid these “remedies” if they are suggested. Pain is sometimes severe, but can be relieved by ice packs, local anaesthetic sprays, ointments (such as lignocaine 5%); use steroid creams if itching is a problem. Beyond these there is little of proven benefit, although people have tried anything from baking soda to meat tenderiser over the years. Antibiotics are indicated if there’s any sign of infection developing

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