question: i saw a doctor today for a UTI that I got last wednesday but was not home to see a doctor for prior to today. After seeing the doctor today I had to wait until 6:30 tonight to get the prescription due to allergies and miscommunication. Anyway at this point my back is hurting very bad. Across my waist area. My question is if it has turned into a kidney infection by now will Cephalexin 500 MG be strong enough to knock out a Kidney infection?