Red dots on the palms of the hands may be caused by allergies, infections and other factors that lead to local capillary dilation or damage, but can also be caused by systemic diseases or hematologic diseases, mostly seen in allergic dermatitis, eczema, allergic purpura, etc., but also seen in insect bites after the formation of insect bite dermatitis, etc.: 1, allergic dermatitis: lesions are mostly confined to the contact areas of the hands, a few can also spread or involve the surrounding areas. It can be manifested as well-defined red spots, erythema, with papules, and in severe cases, papular herpes, itching or burning pain; 2, eczema: often symmetrical distribution, serious cases can also diffuse to the whole body. It is often manifested as erythematous based on pinpoint to corn-sized papules, papules, in severe cases can appear small blisters, lesions are not fixed form, can be fused into a patch, the border is unclear, conscious itching intense; 3, allergic purpura: before the onset of the disease often have upper respiratory tract infection, low fever and other prodromal symptoms, followed by the appearance of red papules, usually within 24 hours can develop into pinpoint to soy-sized purple spots, called purpura ; 4, insect bite dermatitis: after being bitten by mosquitoes, red petechiae, papules or petechiae can usually appear at the local skin, conscious of severe itching, scratching generally can not be relieved, serious cases even occur in systemic allergic reactions. In addition, patients are advised to observe the red spots for several days to see if they clear up. If they persist, it is recommended to consult a dermatologist to determine the type of disease, and then determine if there is any damage to the body and how to treat it.