How long can a person go without urinating before it becomes dangerous?

Urination frequency. As the bladder fills it will get to a certain volume that will trigger it to send a message to your brain that you have to urinate. As long as someone is drinking adequate amount of fluids, holding it in is not terrible. The problem arises if the bladder is not emptying or functioning properly. Overtime increased pressure can effect the kidneys. Kidney disorders can effect urine production.