Why does my left kidney hurts so often?

Kidney Pain: First you need to make sure it is your kidney as on your left side there are other organs that can mimic this such as back pain, lower rib pain, lung irritation (pneumonia) and possibly things related to the kidney. Those with kidney pain commonly are found to have a kidney stone, infection, possibly a blockage of the ureter (hydronephrosis) or even vascular issues. See your doctor first.