What can cause pain when passing urine?

Infection or Stone: The most common cause of pain with urination is likely a bladder infection. Infection causes inflammation and tenderness of the urethra, so urine passing through it burns. Another common cause - especially of the pain is sharp and/or associated with passing lots of blood - is a small kidney stone. Anything that damages the urethra (the tube where urine exits the body) can cause pain.