The deposition of melanin particles on the waist due to mosquito bites or after infection treatment is common in clinical practice as post-inflammatory hyperpigmentation, and is also a manifestation of hyperpigmentation, which can be treated with oral medication, topical medication, and medical aesthetic treatment as follows: 1. Oral medication: oral niacinamide tablets and vitamin C can be taken. 2. Topical medication: topical medication can be chosen from mucopolysaccharide polysulfate cream, as well as a mixture of retinoic acid ointment and urea vitamin E cream. 3. The topical application, as well as the mixture of retinoic acid ointment and urea vitamin E cream for external use. 3, medical treatment: you can choose to go to a regular tertiary hospital for medical treatment, such as acid peeling, photorejuvenation, laser, hydrophobic needle treatment, as well as picosecond, super picosecond treatment. During the treatment period, you need to abstain from spicy and stimulating food and wine, while paying attention to rest and reducing late nights, and when you go out, you must pay attention to sun protection and apply sunscreen or barrier cream externally, as well as playing umbrella, riding in a car, wearing a hat, etc.