Long freckles are related to genetic factors and light exposure. 1. Genetic factor: it is the main reason for the development of freckles, and there is obvious family tendency. If parents have freckles, their offspring will be more likely to have freckles on their face. 2. Sunlight exposure: it is a necessary factor for the occurrence of freckle skin damage. After exposure to sunlight and ultraviolet rays, melanocytes in the skin become larger in shape and their ability to produce melanin is enhanced, which can make the pigmentation deepen rapidly, increase in number and become larger in shape. Generally, freckles do not occur in non-sunlight-exposed areas. 3. Others: The following factors may increase the risk of freckles: men have lower risk than women. Light-colored skin is more prone to freckles, e.g. it is common in white people. People with freckles can avoid excessive exposure to sunlight in their daily life. Patients who are willing to be treated are recommended to go to regular medical institutions and choose appropriate methods for treatment under the guidance of doctors.