Small red dots under the skin of the top of the foot like blood spots and not painful and itchy, may be allergic purpura, blood diseases, liver disease and other causes. 1. Allergic purpura: due to contact with pollen and other allergens, which can cause abnormal immunity and allergic reactions, resulting in increased capillary permeability, small red dots under the skin of the feet can occur without pain or itching. 2. Blood diseases: blood diseases such as idiopathic thrombocytopenic purpura and other blood diseases that cause thrombocytopenia may result in small red dots under the skin on the surface of the feet that are painless and itchy. 3. Liver diseases: such as cirrhosis, hepatocellular carcinoma and other liver dysfunction diseases, can cause coagulation dysfunction, appearing on the surface of the skin of the feet with small red dots painless phenomenon. It is recommended that people with red dots on the top of the feet that look like blood spots and are painless and itchy should go to the hospital in time to get a clear picture of the cause of the disease and receive standardized treatment under the guidance of a doctor.