Splish, splash, you got a rash? It’s not uncommon for a swim in the ocean or a soak in the hot tub to spell trouble for the skin. And summer — when water activities are in full swing and bothersome sea life can thrive — is the prime time to develop a water rash, especially a pool rash, saltwater rash or lake water rash.
While rashes can be itchy and irritating, they’re usually harmless. “Water rashes may make you uncomfortable and put a damper on your summer, but they’re generally not serious and usually can be treated at home,” said Dr. Alissa O’Brien, a board-certified dermatologist at Water’s Edge Dermatology.
A native Floridian, Dr. O’Brien has had a lifetime of personal experience with a number of water rashes. Here, she gives the lowdown on the most common ones, including how to recognize and treat them.
1. Sea lice
If you develop a red, itchy rash under your swimsuit or rash guard after being in the ocean, sea lice may be to blame. No relation to head lice, these tiny, translucent larvae of thimble jellyfish are born during the summer spawning season.
Sea lice can get trapped in your hair or under your swimsuit, which is why the rash is usually most prominent on the neck, back, chest, abdomen, groin and backside. Pressure on the larvae causes them to release their toxins. You may feel a slight prickling sensation. Over several hours, a rash, sometimes called “sea bather’s eruption,” develops.
For immediate relief, look in your kitchen. “Vinegar is quite helpful in neutralizing sea lice and reducing symptoms,” said Dr. O’Brien. “In fact, many Floridians keep vinegar spray on their boat and spray down when getting out of the water. We smell like salad dressing, but it helps!”
The rash usually resolves on its own after a week or two. An oral antihistamine such as Benadryl, along with hydrocortisone cream or calamine lotion, can also ease itching and pain. Cool compresses and a nonsteroidal anti-inflammatory drug (NSAID) such as ibuprofen may help, too.
Some people may experience more severe symptoms, including fever, nausea, diarrhea and chills. “These usually affect children and people with allergies,” said Dr. O’Brien. A doctor may prescribe a steroid in the event of a serious reaction.
Infestations of sea lice come and go. On some beaches, purple flags may warn swimmers of the risk. Wearing as little clothing as possible when in the water — no T-shirts or long shorts, and bikinis for women instead of one-piece bathing suits — can help you avoid a sea lice rash.
2. Chlorine rash
The disinfecting power of chlorine (it’s the same chemical found in household bleach, just in a lower concentration) can strip the protective oils from skin, leaving it dry, red and itchy. In people with eczema, this irritation can cause eczema flare-ups.
Hydrocortisone cream can help tame the symptoms of a chlorine rash. Skin usually calms down after a few days, but you should take a break from the pool until it does to avoid further irritation.
To prevent future rashes from pool water, do more than rinse off when you get out of the pool; shower and wash diligently with a gentle soap to remove some of the film that chlorine forms on skin. If you swim frequently, you may want to purchase a special swimmer’s soap or body wash designed to remove chlorine. Ingredients such as vitamin C break the bonds it forms on skin. Finish up with moisturizer to offset the drying effect of the pool water (the more you get in and out of the pool, the worse the effect is), and reapply it often. Keep in mind that most sunscreens are moisturizing — another good reason to reapply sunscreen after swimming.
3. Swimmer’s itch
This rash can develop after swimming in fresh water, such as lakes, ponds and rivers. It’s caused by tiny parasites, called schistosomes, released by infected snails. The parasites burrow into skin not covered by your swimsuit — you may feel a tingling sensation as they dig in — and trigger an allergic reaction. (Don’t worry, they can’t survive in humans and die almost immediately.) The parasites have been found in lakes in all 50 states but are most common around the Great Lakes.
“The rash shows up pretty quickly, usually within 24 hours, though it happens faster if you’ve had exposure in the past,” said Dr. O’Brien. “You’ll have itchy red dots all over the place from where the parasites got into the skin.” Swimmer’s itch is uncomfortable, but it usually clears up on its own in a few days to a week. In the meantime, you can control the itching with oral Benadryl and hydrocortisone cream.
4. Hot tub rash
You might think nothing can survive in the toasty water of a hot tub, but that’s just not true. “Bacteria love to live in hot water, especially if it’s not chlorinated well enough,” said Dr. O’Brien. Worse still, “The skin is easier to penetrate when it’s warm, so it creates the perfect environment for an infection to develop.”
Hot tub rash, aka hot tub folliculitis, is an infection of the hair follicle by the Pseudomonas aeruginosa bacterium. Most people see breakouts about 12 to 48 hours after being exposed. The bright red bumps, which may be pus filled, can appear on any part of the body that has hair, but they tend to be worse in areas your swimsuit covered.
The rash usually clears up in a few days. “It doesn’t tend to be intensely itchy like some other rashes,” said Dr. O’Brien. But if you find yourself scratching a lot, oral Benadryl and calamine lotion should help. Skip the hydrocortisone cream, since steroids can make infections worse.
5. Jellyfish stings
Jellyfish and the Portuguese man-of-war thrive in saltwater and their stings are common around the Florida coast. Most jellyfish and man-of-war stings usually aren’t very dangerous, but the toxin they release causes immediate pain and burning that can last for several hours. Use these tips immediately after being stung to help reduce the pain:
- Rinse the area with vinegar, which can neutralize the venom.
- Do not rinse with plain water as it can trigger the release of more toxin.
- Do not urinate on the sting; urine can also aggravate the stingers and worsen the pain.
- Use tweezers to remove any tentacles still on the skin. Do not scrape them away with a credit card or other scraping device — you’ll only cause the stingers to release more venom.
Shortly after you’re stung, a line of red welts develops where the tentacle touched you — it can look like you’ve been hit with a whip. You may experience itching and swelling, and some people may develop hives or blisters. Oral Benadryl, NSAIDs and hydrocortisone cream can help reduce pain and inflammation, which should resolve after a week or two.
6. Blue-green algae rash
Blue-green algae, also known as cyanobacteria, is what most people know as “pond scum.” It floats on the top of the water or lies below the surface and can “bloom” when the water is warm and calm. It sometimes produces toxins (cyanotoxins) that can be irritating to skin or trigger an allergic reaction. Coming into contact with it can make skin red, swollen and sore. Small blisters sometimes develop.
Blue-green algae can be found in fresh water, salt water or mixed “brackish” water. If you’re exposed to it, remove any contaminated clothing and jewelry and wash your skin with soap and water for 10 to 15 minutes. Not everyone who comes into contact with blue-green algae develops symptoms, but if you do, antihistamines and hydrocortisone cream can help relieve them.
To protect yourself from these toxic blooms, steer clear of water that’s discolored and smelly or that has green scum on the surface.
Article Written By: Karyn Repinski is a Brooklyn, NY-based award-winning health and beauty writer.
Medical Review By: Alissa O’Brien, MD