Dr Jules Eden, dive medicine specialist and founder of e-med, answers divers' questions - as published in Sport Diver magazine:
Q - I have just got back from Sharm and was stung by a fire coral a week ago, on my second dive of a series of ten. Initially it blistered into large fluid-filled bubbles all over my leg. The doctors at the hotel put white vinegar and iodine on it. Since then the swelling has reduced but there is now a purple discolouration developing around the wound. I have been given an iv injection of steroids, and some gel to rub on, but don't feel any better at the moment. It is not painful but is very itchy and irritated. Is there any other treatment you can suggest as I don't want to be stuck in the hotel missing all my dives!
A - Fire corals are so named because of their similarity in appearance to reef-building coral, but in fact they are carnivorous members of the coelenterates (jellyfish). So in essence the treatment of these stings is the same. Fire corals differ slightly in that they have bright calcified skeletal coverings perforated by millions of tiny pores, through which their stinging tentacles project. Hence people can be injured by scraping themselves against the skeleton, or by being stung, or often both. The symptoms vary from a mild, burning itch to severe pain, and what you see is a reddish swelling around the site, often surrounded with blisters or weals. Occasionally the blisters become pus-filled but most dry and flake off within 24 hours or so. As well as the usual jellyfish remedies, local heat, in the form of a hot towel or hot water, can help to denature the stinging toxin too.
Q - My buddy and I were recently diving in Mexico, which was excellent until the last day. We were hanging onto the shot line doing our safety stop, I had gloves on and she didn't. As she pulled herself up to the surface she cut her hand on something. It was bleeding at the surface but looked clean so we just rinsed it with fresh water and plastered it. It stung a lot on rinsing. It's now 3 days on and she says it's throbbing horribly, and her other hand is covered in red swollen marks. What's going on? Any ideas on how we can get this better?
A - Ah, this bears all the hallmarks of a good dose of the fire corals. Quite often anchor or buoy lines are colonised by corals and hydroids, and the unwitting gloveless diverís hands, softened up nicely after an hourís submersion, are sliced easily by hard coral fragments. Subsequent discharge of thousands of stinging nematocysts and the injection of foreign particulate matter into the wounds leads to a real humdinger of blistering, infection and chronic inflammation. Yuk. So the aim of initial first aid is to clean the wound as much as possible and neutralise the sting (the hypotonic nature of fresh water will actually cause MORE stings to be released). Plenty of vinegar should be used to flush the wound, and a good scrub with soapy water should rid it of most of the retained dirty bits of coral. If itís a deep or large cut then itís probably wise to start some antibiotics, as infection is pretty common. A tetanus shot is a must, and if itís not obviously healing and improving in 2-3 days, itís likely thereís some remnants in there which are causing a secondary reaction. This then requires further cleaning, debridement and probably a trip to the docís for some strong antibiotics. Beware of delayed reactions too: sometimes victims can suffer itching, burning and pain for months, so get in early with some steroid creams and painkillers if these symptoms start to appear.
Q - I have just got back from Sharm and was stung by a fire coral last Friday. It first went into a swollen bubble and they put white vinegar and iodine on it. Since then the swelling has gone down but around the wound there is a red/purple patch. I have been given steroid injections, antihistamines and painkillers at Sharm. It is not painful now but is very itchy and irritated. Unfortunately it is beneath my bottom and the allergy has gone toward my inner thigh (not nice) as I have to sit on it. I will try to attach a picture to this email. Could you please help me.
A - Not to worry, even professional snorkellers get stung from time to time. Fire corals are so named because of their similarity in appearance to reef-building coral, but in fact they are carnivorous members of the coelenterates (jellyfish). The thing all coelenterates have in common is the development of stinging capsules called nematocysts, which either cling to victims via sticky mucus or a hook, or inject venom into prey by penetrating like a needle. Either way, the idea of the nematocyst is to immobilise the hapless chump so it can then be eaten.
Fire corals have bright calcified skeletal coverings perforated by millions of tiny pores, through which stinging tentacles project. Hence people can be injured by scraping themselves against the skeleton, or by being stung, or often both. The symptoms vary from a mild, burning itch to severe pain, and what you see is a reddish swelling around the site, often surrounded with blisters or weals. Occasionally the blisters become pus-filled but most dry and flake off within 24 hours or so.
Plenty of local treatments have fallen in and out of favour over the years. Alcohol was once thought to dehydrate the nematocysts and thus prevent further stings, but studies now suggest it may actively stimulate more discharges. Current fashion is to use vinegar, which seems to reduce the number of stings from a live tentacle, although it does nothing for pain. Local anaesthetic ointment will provide relief however, as will antihistamines and steroid creams for the itch. Local heat, in the form of a hot towel or hot water, can help to denature the stinging toxin too. These are the only remedies for which there is evidence, gleaned from trials involving brave (or foolish) guinea pigs who volunteered to be stung. Lime juice, washing powder and mermaidís milk are unlikely to be of benefitÖ
Q - Hi, I wonder if you could help. Whilst diving in the BVI's 2 weeks ago I received a coral burn on my hand from inadvertently grabbing hold of a rock to steady myself in a swell in a confined space. This was just a minor pins and needles feeling for about an hour after I surfaced. After returning to Blighty the burn seems to have been reactivated by something I must have done - rubber gloves - cat flea spray??? And the whole area has swollen up and is extremely itchy and painful especially in the mornings. As it is my thumb and two first fingers of my right hand I am unable to use them much. I am currently using anti-histamine cream on the area which temporarily helps but it doesn't seem to be going - any ideas of what I should be doing and why it's continued so long.
A - "You're full of pizen, honey", sang poodle haired spandex rockers in the 80's, that desert decade for decent music. Fire coral can be nasty with pain and itching lasting for weeks, and the chance of secondary infection too. My favourite poultice is called Fucibet, a steroid and antibiotic cream. Apply it twice daily. If there is redness and swelling you may need a tablet called Magnapen too. So go show it to the doc, and it would be good to leave off other skin irritants as well. Avoid rubber gloves and cat flea spray by simply hiring a cleaner and buying a gun.
Q - I am hoping you can offer advice on a coral sting received 5 months ago. I am a relatively inexperienced diver, becoming Padi Open Water qualified earlier this year, and on a dive in Bora Bora in June tried to get out of the way of another diver who was heading backwards at me. Unfortunately, I brushed against coral which has left what looks like chicken pox marks all up my arm. I do not know what coral I touched but the pain was excruciating and subsided over a few days.
The dive instructor told me to place lemon juice of the sting and a paramedical that was also diving with us, told me to place hydrocortisone on the sting and take an antihistamine, which I did.
On returning to the UK I visited my doctor who thought the sting was shingles but offered no advice other than if anything was going to happen it would have happened by now!! I am now 5 months down the line and whilst the sting has slowly started to heal the marks are still very evident, more so when I am cold. As my daughter is getting married next year and the embarrassment the marks are causing, I am obviously concerned over the timescale involved.
Please could you advise me whether the marks will clear and if I can do anything to assist in the healing process. Please could you also inform me the procedures if anything like this was to happen again - hopefully not as I intend to stay well clear of any other divers and wear a full suit.
Many thanks for your assistance, in anticipation.
A - Here's the plan. Do nothing. Why? Well if it's the wedding you are worried about, and there are these interesting marks down your arm, what better way of deflecting the conversation away from "doesn't she look beautiful, you must be proud", or "not salmon again" as the buffet looms, than by having ultra cool fire coral scars up your arm and you can then bang on about Bora Bora and which footballer or film star you roomed next to!
These marks can last a long time, years even, so get used to them. And if you want to damage limit the next time, wear a stinger suit, i.e. full 1mm lycra bodysuit if you're there again. Or use Fucibet cream straight away on the area twice a day for a couple of weeks.
Lastly, how your GP could hear a story of immediate rash after a coral burn, and then tell you it is shingles defeats me. You don't have to be clever to go to med school, just know the right people I guess.
Q - I have just returned from a diving holiday in the Red Sea. Last Saturday on my final dive I was stung by Fire Coral on the back of my left leg. I have burns within a 12" by 4" area, which are red and itchy. I have consulted my GP (who has no experience of this condition), who advisedme to use anti histamine cream, which is not having any significant effect.
Please could you advise if there is a more appropriate treatment and how can I get the prescription asap.
A - The treatment for fire coral stings is fairly straight forward in the acute phase.
The pain and rash is caused in a similar way that a jellyfish will cause the problems too. Lots of stinging nematocysts, full of venom, implant into your skin and pump in the poison.
The can be neutralised by vinegar. But in your situation where you are still itching like crazy you need to get some steroid cream. At this late stage I would also make sure there's some antibiotic in the cream too as there may well be itching if you have been scratching the area.
Try "fucibet" cream. Its got a good strong steroid and a broad spec antibiotic. It is only prescribable though, so if you need it asap, then either try e-med, or wait patiently at your doctors.