Beware of Sea Lice
Unfortunately, the ideal season for ocean sports coincides with the season for "sea lice," which are common in some areas of the United States. These sea bathers' eruptions form an itchy rash that scientists believe is caused by jellyfish larvae. The dermatitis usually becomes noticeable between four and 24 hours after exposure, although some may experience a prickling sensation while still in the water.
The only real prevention is to avoid the water when there's a sea lice warning posted. If you or your kids are exposed to sea lice, remove your swimsuits and rinse off with fresh water as soon as possible. It might be a good idea to take several bathing suits with you to the beach and change your children into clean dry suits between swims. With sea lice, you can expect skin irritation with redness and welts, possible flu-like symptoms, fever, and nausea. Hydrocortisone cream and oral antihistamines, such as Benadryl, help to relieve the itching. Check with a doctor if the symptoms become severe.