Stings from the Portuguese man o’ war may result in severe dermatitis, characterized by extremely painful, long, thin open wounds that resemble those caused by a whip, but are not caused by any impact or cutting action, but rather irritating urticariogenic substances in the tentacles. The Portuguese man o’ war is often confused with jellyfish, which may lead to improper treatment of stings, as the venom differs from that of true jellyfish. Treatment for a Portuguese man o’ war sting includes:
*avoiding further contact with the Portuguese man o’ war and carefully removing remnants of the organism from the skin (taking care not to touch them directly with fingers or any other part of the skin to avoid secondary stinging)
*apply salt water to the affected area (not fresh water, which tends to make the affected area worse)
*follow up with the application of hot water (45 °C or 113 °F) to the affected area from 15 to 20 minutes. which has been shown to ease the pain better than ice cold water.
*if eyes have been affected, irrigate with copious amounts of room-temperature tap water for at least 15 minutes, and if vision blurs or the eyes continue to water or hurt, swell, or show light sensitivity after irrigating, or there is any concern, seek medical attention as soon as possible
Source : www.wikipedia.org