The red buttocks is a common inflammatory skin lesion in infants and young children, often occurring in the infant diaper area, and can be caused by the infant’s physique, bacterial infection and allergies.1. Physique and allergy factors: infants and young children have young skin and a thinner stratum corneum, so when there is adverse stimulation or their resistance decreases, it is easy to produce various types of local allergic reactions, resulting in inflammatory lesions such as redness, swelling, blistering, erosion and exudation. This can lead to red buttocks in infants and children. For example, the use of poor quality diapers, which can be a bad stimulus to the skin of infants and toddlers, or not changing diapers for a long time, can also aggravate the symptoms and lead to red buttocks and red and swollen traces on the skin surface of infants and toddlers with the same shape as diapers. In addition, parents who do not change diapers diligently, or do not wash their hips in time after urinating and defecating, can also cause or aggravate the occurrence of infant red buttocks; 2. Bacterial factors: when infants use diapers, they are locally exposed to feces and urine, which contain bacteria and urea, and bacteria can produce ammonia after decomposing urea, which can irritate the skin after evaporation and make infants appear red buttocks.