Conditions
Seabather's eruption: an itchy rash after the ocean
Seabather's eruption is an itchy, stinging rash that appears under your swimsuit after swimming in the ocean. It is a reaction to tiny larvae of jellyfish or sea anemones trapped in the fabric. It usually eases when you take off the swimsuit, shower and use an anti-itch cream. If it does not get better, the doctor can see you by video.
Is it an emergency? Call 911.
Is this an emergency?
This is not an emergency service. Call 911 or go to the nearest emergency room if you have:
- Trouble breathing, or swelling of the face, lips or tongue
- Severe dizziness, fainting or chest pain after a sting in the sea
- Fever with redness that is spreading, hot and painful
Help lines
At a glance
Seabather's eruption
Common symptoms
- An itchy, stinging rash after swimming in the ocean
- Red bumps or spots under the swimsuit
- Stings more when you rub the skin
- Other names
- Sea lice
- Treatment
- Hydrocortisone lotion and, if needed, an oral antihistamine
On this page(8)
What is seabather's eruption?
Seabather's eruption, often called "sea lice", is not caused by lice. According to the Merck Manual, it is an allergic reaction to stings from the larvae of the sea anemone or the thimble jellyfish. It affects swimmers in parts of the Atlantic, including Florida, the Caribbean and Long Island.
The larvae are so small they are hard to see. They get trapped between your swimsuit and your skin and sting when the fabric rubs or presses. That is why the rash appears exactly where the swimsuit touches the skin.
It is different from a jellyfish sting, which leaves tentacle marks on exposed skin: see jellyfish stings. If there is sargassum on the beach, see sargassum and health. And if you have an itchy red line that moves under the skin of your foot after walking barefoot on sand, see cutaneous larva migrans.
How we help by video
You see Dr. Diana Nieves Castro, a Puerto Rico–licensed general practice physician with several years of emergency-department experience, in English or Spanish. The doctor asks where and when you swam and looks at the rash on camera; if she asks, you can send photos through the secure link.
We evaluate, diagnose and treat. The doctor tells it apart from other beach rashes, such as sunburn or heat rash. If appropriate, the doctor prescribes and we send your prescription to your pharmacy.
On vacation on the island? We see you too: see care for visitors. Patients under 21 need a parent or legal guardian on camera with ID.
Your doctor
Dr. Diana Nieves Castro, MD
General practice physician
Several years of emergency-department experience.
Founding Executive Director of The Health Initiative.
Your visit in 3 steps
Request a visit online 24/7 — we confirm your time by email or text.
Request your visit.
Book a visit and choose "Doctor visit". You pay by card when you request it.
See the doctor by video.
We send you a secure video link. It works on your phone, tablet or computer.
Get your plan.
The doctor tells you how to ease the itch and, if appropriate, prescribes and we send your prescription to your pharmacy.
What the visit costs
Seabather's eruption is handled in a US$79 doctor visit, the same price for every age, with no membership. You pay by card when you request the visit, and you get a full refund if the visit can't take place. See prices.
Seabather's eruption symptoms
It appears on the areas your swimsuit covers. In children, if the skin stings when rubbed and the rash is under the swimsuit, the AAP notes it may be seabather's eruption.
- An itchy, stinging rash after swimming in the ocean
- Red bumps or spots under the swimsuit
- Stings more when you rub the skin
What to do: relief and prevention
What the Merck Manual and the AAP recommend:
- Take off your swimsuit, then shower. Do not shower with the swimsuit on.
- Do not rub the skin: rubbing makes the stinging worse.
- Wash the swimsuit before you wear it again.
- For the itch: hydrocortisone lotion and, if needed, an oral antihistamine.
- If the itch is severe or does not improve, see the doctor.
When to go to the ER
For your safety, go to the emergency room or call 911 if you notice:
- Trouble breathing, or swelling of the face, lips or tongue
- Severe dizziness, fainting or chest pain after a sting in the sea
- Fever with redness that is spreading, hot and painful
How we care for you
We evaluate, diagnose and treat; if needed, we give you a lab order for a lab near you.
We see adults and children of all ages. Patients under 21: a parent with patria potestad (parental authority) or a legal guardian is on camera for the whole visit and shows photo ID.
Real-time video visit. We send you a secure video link. It works on your phone, tablet or computer.
If appropriate, the doctor prescribes and we send your prescription to your pharmacy. We do not prescribe controlled substances.
You must be physically in Puerto Rico during the visit (visitors, tourists and cruise passengers are welcome).
In an emergency, call 911.
Frequently asked questions
What are "sea lice"?
How do I stop the itch from seabather's eruption?
Is seabather's eruption contagious?
Can I be seen while on vacation?
About this page
Author: The Health Initiative
Medical care provided by Dr. Diana Nieves Castro, MD (PR license 24027)
Disclosure: Founding Executive Director of The Health Initiative
Published: 2026-10-02 · Updated: 2026-10-02
Sources (3)
- Jellyfish stings and seabather's eruption (Merck Manual) (opens in a new tab) (accessed 2026-10-02)
- 12 Common Summertime Skin Rashes in Children (AAP, HealthyChildren.org) (opens in a new tab) (accessed 2026-10-02)
- Zoonotic hookworm (CDC DPDx) (opens in a new tab) (accessed 2026-10-02)