Sea Lice, Seabather’s Eruption and Swimmer’s Itch

Sea Lice covered in this post from 2011.

Possibly due to the early summer three-week-long heatwave in Ireland, the itching we associated with sea lice has started early in the first week of August instead on late August or September when the problem usually arises.

Sea Lice

Sea Lice

It usually noticed while in the sea. I usually notice the itching in my armpits, along my torso and on my arms. As I said in 2011, sea lice is a generic term and for us in Ireland it is not as severe as other warmer waters. It can mean tiny jellyfish polyps or anemones. Women usually suffer more because whatever the cause gets trapped inside their swimsuits.

Topical skin ointments such as Safe Sea may provide some protection though I can’t vouch for that. Once water temperatures have warmed sufficiently that an immediate post-swim dowsing from a water bottle is unlikely to cause Afterdrop, a shower with fresh water immediately after a swim certainly can reduce or eliminate discomfort. Drying in the Sun without towelling off can also prolong the sensation as the nematocysts of the dead immature jellies can continue to fire on the skin. Regular long duration immersion swimmers may find the symptoms can become much more uncomfortable, appearing like pimples, blisters, hives or even severe hives upon hives.

But sea lice, aka immature jellyfish or anemones, may not be only cause of that late summer open water unpleasantness. The sensation can go by the term Sunbather’s Eruption, for sea swimmers, or Swimmer’s Itch (aka lake itch, duck itch, or cercarial dermatitis and many other names) for fresh water swimmers in warmer climes.

The CDC points out that Swimmer’s Itch may be microscopic parasites, usually from snails, that infect seabirds and mammals, washed into the sea as eggs or larvae which, lacking their preferred host, burrow into human skin, causing an allergic reaction, similar to scabies that afflicts many families of young children.

Lifecycle stages of trematode species that cau...

Lifecycle stages of trematode species that cause “swimmer’s itch”. (Photo credit: Wikipedia)

Like scabies, scratching will inflame the area and worsen the symptoms. Unlike scabies the parasites will at least die naturally and infected people are not infectious. It’s also safe to use a swimming pool if you have Swimmer’s Itch.

For worse cases the CDC recommends a number of possible treatments:

  • Use corticosteroid cream
  • Apply cool compresses to the affected areas
  • Bathe in Epsom salts or baking soda
  • Soak in colloidal oatmeal baths
  • Apply baking soda paste to the rash (made by stirring water into baking soda until it reaches a paste-like consistency)
  • Use an anti-itch lotion

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5 thoughts on “Sea Lice, Seabather’s Eruption and Swimmer’s Itch

  1. Pingback: How To: Understand the Features and Hazards of the Different Types of Open Water Swimming Locations – II – Lakes and Rivers | LoneSwimmer

  2. Pingback: How To: Understand the Different Types of Open Water Swimming Locations Features and Hazards – I – The Ocean | LoneSwimmer

  3. I’ve only ever experienced the itch, thankfully! To put it in perspective, if you bathe in oriental water, especially around Japan, you can be directly infected by the metacercariae of any of three common species of blood flukes – now there’s a nice thought…


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