Black scars left after mosquito bites on legs can be treated by applying 2%-3% hydroquinone cream 2 times/day and instructing patients to avoid excessive sun exposure to reduce hyperpigmentation. When applying hydroquinone ointment, the sensitive body needs to try it on a small piece of skin on the leg first to avoid causing the corresponding dermatitis. Hydroquinone ointment can be enhanced with 0.3% vitamin formic acid ointment to reduce hyperpigmentation. It can be combined with laser treatment, including ruby laser and alexandrite laser, which can absorb and engulf pigment cells, facilitate the shedding of epidermal scabs and improve the color.