Jellyfish, which are almost entirely made of water, are marine animals. There are over 900 species of jellyfish. Their only defence mechanism is a poison found in their tentacles that causes paralysis. When a jellyfish brushes against another animal, a thin tube comes out and pierces its skin. Paralysing venom is then excreted from that tube into the other animal, making it possible for the jellyfish to escape a potential predator. In humans, this venom is usually not potent enough to cause paralysis and is generally the source of superficial damage.
The severity of an injury caused by a jellyfish sting is proportionate to the body area affected. Children, more susceptible to the effects of toxins because they are smaller and more sensitive, often have more serious reactions. Use caution when around jellyfish - even those that have washed up on the beach - as detached tentacles are capable of causing stings. Furthermore, jellyfish toxins can be carried in the water and cause minor burns. Avoid swimming in jellyfish-infested waters!
The areas that came in contact with the jellyfish usually become covered with several whiplash-like lesions. Upon contact with the jellyfish, you might feel an electric shock-like sensation, followed by a burning sensation and acute pain that can increase over 30 to 40 minutes. In more severe cases, pain can be associated with nausea, stomach cramps, dizziness, vertigo, headaches, muscle cramps or breathing difficulty. These symptoms can develop within 2 to 4 hours of being stung. If that happen, seek medical help immediately.
As soon as you feel the sting, get out of the water as quickly as possible. Rinse the area with sea water, saltwater or vinegar but do not rub. Never use freshwater which could make things worse. If tentacles are stuck to the lesion, remove them carefully making sure you do not touch them with your bare hands (use tweezers or wear gloves). Cover the affected area with sand and let dry for 10 to 15 minutes. You could also use salt or sugar instead of sand. This should ease the pain somewhat. The goal of this step is to "trap" the last tiny invisible pieces of jellyfish that could remain on the skin. Remove the sand using a piece of strong cardboard, raking everything out. Finally, rinse the area with seawater a last time. If pain persists, apply an ice bag to the affected area. You could also apply an astringent or over-the-counter 0.5% cortisone cream. The area usually heals within 3 to 10 days. If pain persists, see a doctor.
Here are some things you should NEVER do if you get stung by a jellyfish:
- Do not use a tourniquet.
- Do not cut the skin or try to make it bleed.
- Do not suck on the lesion to draw the venom.
Some people who get stung several times by jellyfish can develop an allergic reaction to the venom. Consequently, if upon a second or third sting you observe a much more severe reaction than the first, it would be prudent to seek medical help immediately.