How long do urinary tract infections last and how can i be sure i have one befor i go to the doctor?

It varies: Usually with urine infections there is a sensation of burning or pain with urination or increase in frequency of urination. Some may have fever, vomiting or belly pain. Sometimes urine infections do not present with any symptoms. Urine infections can last for varied amount of time and it is based on age, health of the body's defense system, other medical conditions the person may have.