Belly button is smelly common in the following cases: first, umbilical inflammation, belly button long-term non-cleaning will lead to the accumulation of things, it will lead to infection becomes smelly, and sometimes also because of improper cleaning leads to skin damage infection, can be treated by cleaning the dirt, local intermittent rubbing iodophor or Bactroban and other drugs, but if the redness and swelling is serious, and even obvious oozing, you need to go to the hospital in a timely manner surgical treatment, if necessary, debridement, and later with antibiotics. Later on, antibiotics will be used for treatment. Second, the umbilical ureter cyst, a congenital developmental abnormality, in the embryonic period, the umbilicus and the bladder have a channel to connect, but at birth the tube will be atretic, if not atretic, there will be a continuous accumulation of urine under the skin of the umbilicus, and eventually cause infection, you need to go to the hospital to perform the relevant examination and then surgical treatment. In short, if there are persistent abnormalities in the umbilicus, you need to go to the hospital promptly.