A few days ago, a parent brought her 16-year-old son, Xiao Qiang, to our department for treatment. Just after entering the door, the mother said to me anxiously, “Doctor, take a look at your child, why did he get so many rashes all of a sudden, is he allergic to something? I first calmed the mother down a little and then asked about Xiao Qiang’s situation. It turns out that Xiao Qiang went swimming with his parents to the Beidai River during the summer vacation, just an hour into the water to play, the legs suddenly appeared red rash, accompanied by a significant tingling sensation, and a few minutes later even wheezing and other uncomfortable performance. In an emergency, the family rushed back to Beijing for medical attention. Xiao Qiang had no history of allergy to seafood, and the family had no chronic allergic diseases such as allergic rhinitis, asthma, or eczema. At this point, I began to carefully examine Xiao Qiang and determined that the red rash was “acantholytic dermatitis”. In addition to allergy-like lesions, acantholytic dermatitis has some important manifestations that are different from allergies: most of the lesions appear in contact with seawater, most often on both lower extremities, while less accessible areas such as the head and face are often not involved. Local lesions mainly appear as erythematous, papular, and pemphigoid damage, and in severe cases, petechiae, blisters, or macules may appear. The most important thing to remember is that most of the lesions of stinging cell dermatitis are dotted, striped, or even whiplash-like in distribution, which helps us to differentiate them from common eczema. The skin of a jellyfish sting will suddenly appear as a lightning-like pins and needles sensation, and within a few minutes there may be itching discomfort, numbness, burning and other sensations. The reason for this is that stinging cell dermatitis is a skin injury caused by the stinging cell animal sticking into the skin and injecting venom into the body when it comes into contact with the human body. The disease is high in the summer season every year, often in aquaculture, fishing, processing and swimming in the sea. The common types of stinging cell dermatitis include jellyfish dermatitis, hydroid dermatitis, sea anemone dermatitis, and coral dermatitis. After being stung by a stinging cell, the cell will release its venom into the body and the local skin will show the above skin damage. If the whole body is stung, the child may have difficulty breathing, chest tightness, cold sweat and other uncomfortable symptoms. The child’s own ability to metabolize venom is poorer than that of adults, so when a child is found to be stung, he or she should seek medical attention promptly. Treatment: Once stung by a stinging animal, first scrape away the stinging cells as soon as possible with a towel, clothes, mud, etc., and rinse the stinging cells stuck to the skin with seawater. Parents should be reminded not to use fresh water to rinse off the stinging cells, as the sudden change in osmotic pressure will cause the cells to release more venom. Then, use alum water, 1% ammonia or 10% sodium bicarbonate solution as much as possible to neutralize the venom with wet compresses. This can be followed by topical glucocorticoid ointment (e.g., mometasone furoate cream) to improve itching discomfort. Oral antihistamines (cetirizine drops or loratadine syrup) are recommended in cases of extensive lesions, severe immune response, blistering and intense itching. If irritability, pallor, wet and cold hands and feet, wheezing and decreased blood pressure occur, prompt hospital consultation for anti-shock treatment should be sought. The continued hot weather has given parents who are ready to take their children to the beach for a summer swim a heads up that they should choose a clean seawater area for summer bathing and educate their children not to push with their hands when they encounter jellyfish floating in the water. If you find that your child has the characteristic erythema, accompanied by itching and stinging discomfort, you should think about the possibility of stinging cell dermatitis, and go to a regular hospital dermatology department in time to avoid the aggravation of skin lesions, and even the possibility of systemic poisoning symptoms.