There will be red dots on the hand to consider the physiological spider nevus caused by excessive estrogen, or consider contact dermatitis, allergic purpura and other diseases. 1. Physiological spider nevus: Adolescent women are in the stage of growth and development, the body will secrete too much estrogen, physiological spider nevus can appear. With the growth of age, spider nevus can disappear on its own. Spider nevus is characterized by small red dots on the hands. 2. Contact dermatitis: its cause is related to chemical stimulation, soap, detergent, leather, flowers, animals and other factors. Patients can appear in the local erythema, pinpoint size dense papules, which can be manifested as red dots on the hands. 3. Anaphylactic purpura: its cause may be due to infection, drugs, heredity, environmental stimuli and other factors. Patients may have purplish-red papules on the skin, manifested as small red dots on the hands. There are many causes of red dots on the hands, and it is recommended that patients go to a regular hospital to find out the cause of the disease.