When the day is hot, bumps on the body, may be heat urticaria, cholinergic urticaria, can also be considered related to mosquito bites. 1. Thermal urticaria: Thermal urticaria is an allergic disease, also belongs to a kind of physical measles. When the weather is hot, the skin mast cells degranulate, which can cause itchy skin, and also lead to the appearance of windburn and erythema on the skin. 2. Cholinergic urticaria: cholinergic urticaria is also a kind of urticaria, the skin is heated, the body heat production increases, can cause obvious itching, scratching leads to localized edematous erythema, wind. 3. Mosquito bites: the weather is getting hotter and hotter, mosquitoes are more and more, if you do not pay attention to the protection of the skin by mosquito bites, may lead to red bumps on the skin with itching. Days a hot body pimples suggest not to scratch stimulation, but also to the hospital dermatology examination, as prescribed by the doctor to give anti-allergic drugs, such as loratadine and other drugs.