Pimples from the ocean

After being in the ocean I break out in pimples on the forehead. I'm 43 and started happening about 10 years ago when I got mild rosacea. If I wash my forehead with fresh water within say 20 minutes of getting out of the water I won't be affected. It doesn't seem to matter how long I'm in the ocean for - as far as I can tell it happens if the salt water is allowed to dry for a certain time. It doesn't much worry me since the pimples (and a little redness surrounding them) aren't severe and are generally totally avoided, but I'm curious to understand what is happening because I haven't heard of anyone with similar symptoms, and a quick internet search of pimples and salt water gives many claims of the salt being beneficial for avoiding pimples, and none of the opposite. I also after salt water generally get a few tiny pimples on the nose abut none at all elsewhere.
Thanks for any thoughts.

[smeagol84]

I should have added that the pimples appear about 6 hours after coming out of the ocean, and continue to appear for roughly 18 hours after first appearing.
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[Bhupinder Kaur, MD]

Hello,
Since you are having these symptoms only after entering the sea water, so it looks like an allergic reaction to the constituents of sea water like cold water of the ocean or to the inorganic and organic contents of the ocean water. The inorganic contents are the various mineral salts found in the ocean water and the organic contents are the algae, protozoans and the planktons.

Take some antihistaminic like Benadryl and apply calamine lotion. Also avoid the sea water on your face for long and wash your face with fresh water immediately after being in the sea.

It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.