Background: Jellyfish are distributed worldwide; they cause local skin injuries upon contact which are often followed by systemic signs of envenoming.
Objectives: Which jellyfish species are of medical importance, which skin reactions and systemic symptoms occur, which first-aid measures and treatment options exist?
Methods: Review of the medical literature and discussion of first-aid and therapeutic options.
Results: Jellyfish capable of causing skin injuries occur in almost all oceans. Several jellyfish species may cause severe, potentially lethal, systemic symptoms; they include the Portuguese man-of-war (Physalia physalis) and box jellyfish (Chironex fleckeri, Carukia barnesi, Chiropsalmus quadrigatus).
Conclusions: Among the injuries and envenoming symptoms caused by marine organisms, jellyfish dermatitis should not be underestimated. Skin reactions may not only a dermatological problem, but also be accompanied by complex systemic toxic symptoms which are a challenge for internists.