Running a temperature. When you suffer from a bladder infection, your body’s immune system will begin to respond. As the infection progresses, this response will become more intense, sending your entire physiology into a heightened state of function. This will cause you to run a fever. It goes without saying that if you find yourself running a slight temperature, seemingly without reason, you should suspect that you are suffering from an infection. If the other symptoms that you observe correlate with a bladder infection, the diagnosis then becomes certain.