Red dots on the skin may be caused by allergy, eczema, spider nevus and so on. 1. Allergy: when the human body comes into contact with certain substances after the immune response, the body through skin contact, inhalation, ingestion and other ways of contact with allergens, will lead to patients with red dots on the skin, the patient’s main manifestation of itchy skin, a small number of patients with edematous erythema. 2. Eczema: when patients are affected by external stimuli, such as ultraviolet rays, food, pollen, animal fur and other factors, resulting in patients with red spots on the skin, accompanied by erythema, itching, skin thickening and other symptoms. 3. Spider nevus: red spots on the skin may be caused by spider nevus, but they are small and few in number, and most of them will persist. It is recommended that patients go to regular hospitals, under the diagnosis of the doctor, according to the patient’s specific condition performance, targeted treatment.