There are relatively more reasons for the darkness of the skin on the chin, such as inadequate sun protection, pigmentation spots, improper use of medication, eczema and other factors. 1. Inadequate sunscreen: If you don’t do a good job of sunscreen when you go out, especially in summer when ultraviolet rays are strong, your chin will be exposed to ultraviolet rays, resulting in hyperpigmentation. 2. Pigmentation spots: due to uneven distribution of skin melanin particles caused by local skin color is heavier, showing spots, sun exposure, improper use of cosmetics, etc. are causes of pigmentation spots, which can lead to dark skin on the chin. 3. Improper use of medication: If you use hormone creams to smear the chin area because of disease, it will cause the chin skin to be irritated and cause the skin to be black. 4. Eczema: If the patient is exposed to some allergic substances can easily lead to chronic eczema, the symptoms of which are characterized by hyperpigmentation, itching and so on. There are many other causes of dark skin on the chin, it is recommended to consult a doctor in a timely manner to avoid blindly using medication on their own.