Jellyfish, also known as jellyfish, is a common sea gelatinous animal and a delicious dish on the dinner table. The arrival of summer makes the seaside bath a good place for people to cool off. It is also the high season for jellyfish dermatitis. Jellyfish tentacles have a large number of stinging cells, which contain venom, the composition of which is mainly protein-like, polypeptide and a variety of toxic enzymes, in addition to a strong anesthetic, analgesic, histamine and so on. When the human body contacts the jellyfish tentacles, the stinging cells can pierce the skin, causing stinging cell dermatitis, which can lead to death in serious cases. Swimmers with exposed limbs stung by jellyfish sting, feel tingling, burning pain or itching, followed by the sting appeared in a striped arrangement of erythema, pimples, blisters, blisters and petechiae, ecchymosis. In mild cases, the rash may subside in 1-2 days, and in most cases, the rash will scab over in 1-2 weeks. If the whole body is stung in many places or stung by large jellyfish and jellyfish with strong toxicity, often within 1-4 hours there are chills, fever, abdominal pain, lethargy, cold sweats, a few chest tightness, foaming at the mouth, decreased blood pressure, respiratory distress, pulmonary edema, and in severe cases, can lead to death. Once stung by jellyfish, do not rinse with fresh water, as fresh water can prompt the release of venom from the stinging cells. You should use towels, clothes, mud and sand to wipe off the tentacles or venom adhering to the skin as soon as possible, and you can also use seawater to rinse. If possible, the affected area can be rinsed or sprayed with alcohol or alkaline lotion, such as 10% sodium bicarbonate. For those with large skin lesions and serious systemic reactions, they should go to the hospital in time for treatment.