Seabather’s Eruption

Seabather’s eruption is an itchy, sore rash. It's caused by stings from tiny jellyfish. These tiny jellyfish are found drifting in the ocean or other saltwater. They are the size of a pinhead and have stinging cells. They get trapped against your skin by a swimsuit, wetsuit, or your hair. The stinging cells release toxins when they are squeezed or rubbed, exposed to fresh water, or dry out in the air. These toxins can cause an allergic reaction in some people with sensitive skin.

The reaction often starts as a tingling feeling under your bathing suit, while you are in the water. A few hours after leaving the water, you will feel an itch. This is followed by a red, bumpy, painful rash. The rash can last several weeks.

If you have been exposed to this before, your next reaction may be worse. Symptoms may include extreme tiredness (fatigue), nausea, headaches, fever, chills, weakness, vomiting, itchy eyes, and a burning feeling when urinating.

Seabather’s eruption is most common from March to August, when there are more jellyfish. It's not contagious. This means it can’t be passed to someone else who touches it.

Over-the-counter anti-itch medicines are used to treat symptoms. Most reactions get better in 1 week. Some cases may take longer.

Home care

  • Remove your swimwear to rinse off. Then put diluted vinegar or rubbing alcohol on the affected area.

  • Stay away from anything that heats up your skin (hot showers or baths, direct sunlight). This can make itching worse.

  • For itching and pain, put an ice pack or a cold compress on the area. This should be done for 15 to 30 minutes, 3 times a day. To make a cold compress, dip a face cloth into a mixture of 1 pint of cold water with 1 packet of colloidal oatmeal (sold at pharmacies). Keep the solution refrigerated to use later. To make an ice pack, put ice cubes in a plastic bag that seals at the top. Wrap the bag in a clean, thin towel or cloth. Never put ice or an ice pack directly on your skin.

  • If large areas of the skin are affected, take a lukewarm bath. Add 1 cup of cornstarch or colloidal oatmeal to the water. This can be very soothing for children.

  • Put on 1% hydrocortisone lotion or cream (no prescription needed). Use this 2 to 3 times a day for 1 to 2 weeks, unless another cream was prescribed.

  • Use over-the-counter oral antihistamines that have diphenhydramine. Unless a prescription antihistamine was given, these may be used to reduce itching if large areas of skin are affected. This medicine may make you sleepy. Use lower doses during the day and higher doses at bedtime. Some antihistamines make you less sleepy. These are a good choice for daytime use. Don’t use antihistamines that have diphenhydramine if you have glaucoma, or if you are a man with trouble urinating due to an enlarged prostate.

  • Use over-the-counter medicine for inflammation and pain, unless another medicine was prescribed. If you have long-term (chronic) liver or kidney disease or ever had a stomach ulcer or GI (gastrointestinal) bleeding, talk with your provider before using these medicines.

  • Clip and smooth children’s fingernails to keep them from scratching the skin.

  • Machine-wash swimsuits with detergent and machine-dry. 

  • Remember that the stinging cells are not living. But they can be trapped in clothing for a long time. They can still release toxins for weeks after you have washed and dried the clothing.

  • If you had a severe reaction, throw away your swimwear. Then you won't be re-exposed to the stinging cells that may be trapped there.

Prevention

  • Before swimming in saltwater, check local beach reports for warnings of seabather’s eruption. If you have a history of a severe reaction, don’t swim in the water.

  • When swimming in saltwater, women should not wear 1-piece swimsuits. These can trap more jellyfish. Wear a suit with a smooth, tight weave. Don't wear a T-shirt over your bathing suit. That can also trap more jellyfish. As soon as possible after swimming, take off your swimsuit.

  • Most stings occur from contaminated swimwear. As soon as possible after leaving the water, change out of your swimsuit. Then shower. Don't shower with fresh water while wearing your swimsuit. This will trigger the stingers. Pat dry with a towel. Don’t rub your skin. Put on dry clothes.

  • Bathing suits must be washed with detergent and then heat-dried as described above.  

Follow-up care

Follow up with your healthcare provider, or as advised.

When to get medical advice

Call your healthcare provider right away if any of these occur:

  • More redness or pain in the area of the rash

  • Fluid drainage or crusting of the rash

  • Repeated vomiting

  • Burning when you urinate

  • Fever of 100.4°F (38°C) or higher, or as directed by your provider

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