New Study Prompts Changes To Irish Jellyfish Sting Advice

Portuguese man o’ war in glass at Derrynane Co. Kerry, Ireland in September 2016. Photo: Vincent Hyland
May 02 2017 Posted: 13:05 IST

For nearly a decade, the standard practice in Ireland for treating stings by the Portuguese man o’ war jellyfish (Physalia physalis) is to rinse with seawater and then apply ice. However, in a new study published last week, scientists from NUI Galway have found those measures are actually among the worst things to do if stung.

Collaborating with jellyfish sting experts from the University of Hawai‘i – Mānoa, the NUI Galway scientists re-evaluated which commonly recommended first aid actions (such as rinsing with seawater) are the most effective for Physalia stings. Their results, published in the international journal Toxins, overturn the current advice, and show that the best first aid is to rinse with vinegar, to remove tentacles and then immerse in 45°C (113°F) hot water (or apply a hot pack) for 45 minutes.

There are two species of Physalia, the Portuguese man o’ war (Physalia physalis) which occurs in the Atlantic, and the bluebottle (Physalia utriculus) which occurs in the Pacific. Both species are among the most recognisable stinging jellyfish with their bright blue tentacles and colorful inflated floating sails. Just last September, armadas of these painful stingers came ashore in Ireland. Taxonomically speaking, the Portuguese man o’ war is not a true jellyfish but a siphonophore, a closely related group of colonial animals.

Dr Tom Doyle, Lecturer in Zoology from the School of Natural Sciences at NUI Galway, said: “We had unprecedented numbers washing up from Cork to Donegal last September. Thankfully we had very few reported stings given the time of year. However, if this event had occurred during the summer months, then we may have had hundreds of stings. Our new evidence-based research conclusively shows that the best first aid for a man o’ war sting is rinsing with vinegar or a Sting No More Spray, developed by the University of Hawai‘i – Mānoa, followed by the immersion of the injured area in hot water or the application of a hot pack.”

But although man o’ war stings are common around the world, there was little agreement on the best first aid responses to such injuries until now. Dr Tom Doyle and PhD student Jasmine Headlam at NUI Galway collaborated with Dr Christie Wilcox, lead author of the paper and postdoctoral fellow with the Pacific Cnidaria Research Laboratory at the University of Hawai‘i, and her colleague Dr Angel Yanagihara, assistant research Professor at the University’s Pacific Biosciences Research Center. 

Commenting on the research, Dr Wilcox, said: “Physalia are often listed as exceptions to any blanket first aid recommendations for jellyfish stings. Without solid science to back up medical practices, we have ended up with conflicting official recommendations around the world, leading to confusion and, in many cases, practices that actually worsen stings and even cost lives.”

Dr Wilcox and Dr Yanagihara first examined box jellyfish, some of the deadliest jelly species in the world, finding that common practices such as applying urine or scraping away tentacles only make stings worse. Applying these new rigorous testing methods to man o’ war stings was the obvious next step, in which they collaborated on with Dr Doyle at NUI Galway.

In 2008, Dr Doyle set up the Jellyfish Advisory Group, an expert coalition that developed the Irish guidelines for the treatment of jellyfish stings as part of an Ireland Wales INTERREG project EcoJel. He was instrumental in implementing the current sting response protocols and was keen to ensure that Irish medical practitioners are giving the best care possible to sting victims. Dr Doyle added, “In the coming weeks, I look forward to meeting with members of the Jellyfish Advisory Group to discuss our new findings and how we can revise the current protocols.”

Dr Doyle met Dr Yanagihara at a jellyfish conference in Japan and together they proposed a project to the International Fulbright Specialist program, and Dr Yanagihara was awarded a Fullbright Specialist Award to come to NUI Galway to share newly developed assay techniques with the NUI Galway research team. Dr Doyle and Ms Headlam performed experiments using the Atlantic man o’ war in parallel with those conducted by Dr Wilcox and Dr Yanagihara in Hawai‘i.

The results from opposite sides of the world aligned beautifully. The venom delivered by a man o’ war sting was lessened if the sting site was rinsed with vinegar, regardless of which species of Physalia was used. The scientists showed that vinegar inhibited the animals’ stinging cells from firing, thus safely removing tentacles and stinging cells that can remain adhered to the skin and continue to deliver venom over time.

Meanwhile, PhD student Jasmine Headlam is already working on her next research project. “After the Portuguese man o ‘war, the most venomous jellyfish in Irish waters is the lion’s mane jellyfish”, she explained. Lion’s mane (Cyanea capillata) are responsible for more bad jellyfish stings in Ireland than any other species, and in many such cases, the victims end up in the hospital. Ms Headlam added, “We are currently doing similar experimental work on the lion’s mane jellyfish and hope to submit this work for publication in due course.”

To read the full study in Toxins visit: and

View this short video which summarises the results of the study:


Marketing and Communications Office


Featured Stories