First Aid & Emergencies

Itchy Rash or Deep Sore After a Contact With Jellyfish or Portuguese Man-of-War

The rash and skin irritation that occurs with minor jellyfish or Portuguese man-of-war stings will usually go away with home treatment. Seabather's eruption is a rash that develops from the stings of jellyfish or sea anemone larvae. Although these rashes are annoying, they are not a serious medical problem.

When an itchy rash occurs several days to weeks after a sting, the rash may mean a delayed skin reaction has occurred. A delayed reaction can occur many times over the course of 1 to 2 months following a sting. You may have a fever, weakness, or joint stiffness or swelling. Medical treatment may be able to ease the discomfort and prevent complications from a delayed reaction.

Jellyfish or Portuguese man-of-war stings may cause blisters or small, shallow sores (ulcers). The skin at the site of the stings may look dusky or bluish purple. Healing may take many weeks. Permanent scars may occur at the site of a sting.

Sores usually heal without medical treatment. Wounds should be cleaned 3 times each day and covered with a thin layer of antiseptic ointment. But when a deep sore develops, you may need medical treatment to help the sore heal and prevent infection.