Patients with allergy will have erythema, papules and blisters all over the body, and allergy relief will leave pigmentation, and black marks will appear on the previously inflamed erythema. If it appears on the exposed parts of the forehead and face or limbs, it will seriously affect the aesthetics of the patient. The following ways are needed to relieve the deepening of skin color after allergy: First, mediate from the diet and eat more vegetables and fruits rich in vitamin C, such as tomatoes, cucumbers, dragon fruit, apples and carrots. Secondly, pay attention to sun protection, wear hats, masks and sunscreen for pigmentation to prevent further aggravation of the black marks, which can be relieved locally by applying 5% hydroquinone ointment for about several months. Patients with facial melanosis affecting the aesthetics can choose carbon dioxide laser to crush melanocytes locally, thus relieving the symptoms.