Updated July, 2021.
Jellyfish are simple sea creatures with a dome and tentacles. They move by pulsating their body but are at the mercy of tides and ocean currents. The tentacles are the ‘business end’ of the animal that contain a stinging mechanism. In some species, these may be a few metres long.
Their numbers and species range are increasing around UK waters due to warmer seas through global warming. Jellyfish are more prevalent during the summer months as they move north with the seasonal warming of the sea. They can occasionally appear in very large numbers as they congregate in parts of the sea to feed on the increased food supply.
This means they are sometimes found off popular beaches in large numbers leading to swimmers being stung. They are also found on the beach after storms or heavy rains.
In the UK, we typically have three commonly found Jellyfish:
Why do jellyfish sting?
The sting mechanism in the tentacles of the jellyfish is very sensitive and is triggered very quickly to defend themselves or sometimes to catch prey. The venom within the cells acts quickly on the victim, be it prey or a passing human.
The tentacles of the jellyfish contain nematocysts that contain a coiled, hollow, usually barbed, venomous thread which is discharged especially for catching prey and defending against enemies and sometimes helps with locomotion. The barbed nature of these cells means they often stick to your skin and need to be removed quickly and carefully to prevent further venom injection.
What happens when you get stung by a jellyfish?
The majority of jellyfish stings can be treated with some basic first aid. The main signs and symptoms after a jellyfish sting are burning, throbbing and itching and this may spread over the initial infected area as the venom moves through your body.
Other signs and symptoms include tracks or marks where the stings have been.
None of the jelly fish usually found in UK waters are severely toxic, but younger people and people with compromised immune systems may suffer more from stings.
How to treat a jellyfish sting:
- First remove the sting. It is usually easiest to scrape the sting away with a stick or credit card – something with an edge. Slide or scrape the edge along your skin to remove the stuck tentacles. Don’t try and pick them off with your hands. The stings can still cause irritation even after they are detached from the jellyfish itself – so take care not to touch the stick or card afterwards and make sure you discard or clean it straight away.
- Next, rinse the affected area with sea water to wash away any residual stings.
- Heat can help to reduce the pain, so immersing the affected area in warm water (more than 45degC) as soon as possible can be a good idea, or applying a heat pack until the pain subsides. A good hot shower will help greatly. This may seem counter intuitive but the proteins in the venom from the jellyfish will be broken down by the heat.
- The NHS no longer advises using vinegar to treat jellyfish stings. Plenty of sea water then hot water as above.
- Over the counter medicines may help with pain relief and itching. Ask your pharmacist for advice.
More serious signs and symptoms that need medical attention include:
If you have a jellyfish sting on your face or genital area, go to hospital for treatment.
If the stinging is severe, pain is not subsiding or there are any other symptoms or more severe reactions, call 999/112 as soon as possible. Taking a photo of the jellyfish if possible can help medical staff to identify it and give the appropriate treatment.
If you have trouble breathing, a swelling of the face, chest pain or vomiting, severe dizziness then you should go to hospital immediately.
Occasionally more harmful jellyfish are found in UK waters having been brought in on ocean currents and the treatment is the same as for our native jellyfish.
Important things to remember about jellyfish:
They can still harm you even when they’re ‘dead’ on land as their stings are still ‘loaded’ and harmful. Sometimes they may look dead but are actually beached and are still alive. Don’t experiment to find out!
Lastly, contrary to popular belief (thanks to the TV series Friends), do not urinate on a jellyfish sting on a casualty – or yourself – it won’t help! The idea of urinating on a jellyfish sting is a myth and may even make the pain worse by mixing the acids and ammonia from the urine with the venom from the jellyfish.