Sea Lice Stings: What They Are, What They Look Like, and How to Treat Them
If you’ve been for a swim in the ocean lately and come out with an itchy red stings that are driving you mad, you may have had a run-in with sea lice ā one of Australia’s most annoying sea creatures. And in fact, sea lice stings can happen all over the world.
What Are Sea Lice?
Despite the name, what we call “sea lice” are not lice at all. Real sea lice are parasites that infest salmon (do yourself a favour and don’t Google that). What we’re dealing with here are actually the microscopic larvae of jellyfish ā colourless, minuscule, and virtually impossible to see, let alone photograph.
These tiny creatures carry the same stinging cells as adult jellyfish. The scientific name for these cells is nematocysts, and when they fire, you know about it.
Sea lice tend to be most prevalent during the warm summer months, sometimes in very large numbers.
What Do Sea Lice Stings Look Like?
“Sea lice stings” is actually a misnomer ā what you’re experiencing are lots of tiny stings that produce a rash. Historically, this was known as seabather’s eruption, and the technical term for the rash is pruritic dermatitis. The rash presents as red, itchy, raised bumps in the areas covered by your swimsuit. It is typically very uncomfortable, lasting anywhere from two to four days, though some unlucky swimmers may find themselves itching for up to two weeks.
Occasionally, other symptoms such as fever, fatigue, sore throat, and abdominal discomfort can occur ā these tend to be more common in children than adults. Children under 15 may experience more pronounced symptoms generally, partly because they tend to spend more time in the water.
Can You Feel Sea Lice While Swimming?
You might feel a few small stings when you first swim into a patch of larvae, but after that, you’re unlikely to notice much in the water. The real trouble starts later ā symptoms can appear anywhere from a few minutes to around six hours after leaving the ocean, with an itchy rash appearing in the areas covered by your swimsuit.
This is because the larvae get trapped in your costume and fire off their nematocyst cells against your skin. As the swimmer gets out of the sea, water drains out of the bathing suit, trapping the organisms between the suit and the skin, and the pressure causes the stinging cells to discharge. The covered areas cop the worst of it.
Worth noting: the rash is an allergic reaction to the toxins released, and if you get seabather’s eruption more than once, the reaction can actually get worse each time. So it pays to take prevention seriously.
How to Treat Sea Lice Stings
The golden rule: don’t scratch, and don’t rub the affected area ā this can cause any remaining larvae to sting further. Here are the steps to take and things that can help:
- Remove your swimsuit immediately ā this is the most important first step
- Rinse off with seawater first if possible, as an immediate rinse with fresh water can sometimes cause additional stinging from organisms still on your skin
- Once you’ve done an initial rinse, shower with soap and scrub the skin thoroughly
- Apply diluted vinegar or rubbing alcohol to help neutralise any remaining toxins on the skin
- Use ice packs to soothe the sting
- Apply 1% hydrocortisone cream two to three times daily ā this is considered the most useful treatment
- Take an antihistamine, as the rash is essentially an allergic reaction and antihistamines can help ease symptoms
- Ibuprofen or paracetamol can help with pain and inflammation
- Stingose spray or cream is also very effective
- For severe rashes, see a dermatologist, who may prescribe a stronger topical or oral corticosteroid
If the rash becomes red, hot, or increasingly sore, see a GP promptly ā it may have become infected.
How to Avoid Sea Lice Stings
If you feel those telltale mini stings while swimming, take action as soon as you leave the water. Here’s what to do ā and what NOT to do:
Do:
- Remove your swimsuit before showering
- Rinse with seawater before a freshwater shower
- Wash your swimsuit in hot, soapy water after every swim in affected conditions, and dry it in a dryer if possible ā for a severe case, consider throwing the swimsuit out entirely
- Rinse the costume in vinegar or rubbing alcohol before washing
Don’t:
- Shower while still wearing your contaminated swimsuit ā freshwater triggers nematocyst discharge, which can make symptoms significantly worse
- Rub your skin with a towel while still in your swimsuit
- Put a wet or unwashed swimsuit back on ā nematocysts can survive in damp fabric for up to a week
One-piece swimsuits and T-shirts worn in the water increase the surface area exposed to stings and can lead to more severe reactions, so if you’re in an area known for sea lice, a minimal swimsuit is actually an advantage.
And the ultimate (if slightly impractical) solution? Swim nude. No swimsuit means nowhere for the larvae to get trapped. For those not keen on that option, sticking to winter swims is another workaround, as sea lice are far less common in cooler months. If sea lice warnings or flags are posted at a beach, the safest option is simply to stay out of the water that day.
Where in the World Do Sea Lice Occur?
If you’re suffering from sea lice stings in Sydney, you’re far from alone ā seabather’s eruption is a worldwide phenomenon found wherever warm coastal waters exist. Here’s where it’s been documented:
Caribbean, Florida, Mexico and the Gulf States
This is the most heavily studied region for seabather’s eruption and where it is most prevalent. The condition is especially common from March through August, peaking in May and June when larval concentrations are at their highest in nearshore waters.
Eastern USA
A related species ā the sea anemone Edwardsiella lineata ā causes seabather’s eruption along the US east coast from the mid-Atlantic states up through New York, particularly off Long Island.
Brazil
Cases were first reported in Brazil in 2001 and have been documented in the country’s southern coastal regions.
Papua New Guinea
The thimble jellyfish responsible for most cases has also been reported in Papua New Guinea’s waters.
Asia and East Africa
A closely related jellyfish species, Linuche aquila, found anywhere between Malaysia, the Philippines, and the east coast of Africa, is also known to cause seabather’s eruption.
Australia
Swimmers in Queensland have reported seabather’s eruption during summer months, and it is well-known along the NSW coast, including Sydney’s beaches ā as this article can attest!
New Zealand
Swimmers at east-coast beaches of Auckland and throughout the Hauraki Gulf can experience seabather’s eruption, typically during the summer months.
In general, the condition has now been reported across many tropical and subtropical waters worldwide. Scientists believe that in different parts of the world, different local marine creatures may be responsible ā so sea lice are truly a global swimmer’s hazard.
Australia has no shortage of creatures that will bite, sting, or otherwise ruin your day ā but sea lice are manageable once you know what you’re dealing with.
Happy swimming!
PS Sorry about showing you my bare tummy.
Read more about swimming adventures here.
