Baby butt crack redness may be caused by diaper rash, eczema, prickly heat and so on. 1. diaper rash: baby’s skin is relatively delicate, if wrapped in a long time in a moist and breathable environment, such as diarrhea, diaper replacement is not diligent or washing is not clean, etc., can lead to contact with the diaper area of the skin redness, swelling and other symptoms, which can cause the baby’s buttock crack redness. 2. Eczema: an inflammation of the skin caused by a variety of internal and external factors, if it occurs in the buttocks, it can also cause redness of the baby’s buttocks, but also accompanied by pimples, papules, blisters, itching, vesicles, oozing, thickening of the skin and other symptoms. 3. prickly heat: it occurs in summer, in the high temperature environment and diaper wrapped situation, sweat is not easy to evaporate, thus forming prickly heat, will also cause the baby butt crack red. There are many other causes of redness in the baby’s buttocks, which should be taken seriously, and prompt medical attention should be paid to identify the cause of the problem and further treatment or therapy as prescribed by the doctor.