Renal colic is a common condition in which a person with experiences severe pain due to a kidney stone. Kidney stones are small bits of hard crystallized material that form in the kidney. The human body has two kidneys. The kidneys are vital organs that filter waste products from the blood to make urine, which then flows from the kidneys into small tube called ureters into the bladder. The bladder stores urine until it is eliminated from the body through the urethra.

One or more kidney stones can form in one or both kidneys and result in renal colic. A person with a small kidney stone may be unaware of the condition, and it may pass in the urine out of the body without causing renal colic or other problems. In addition, there is generally no pain due to large kidney stones that remain in the kidney. However, when a large kidney stone moves out of the kidney into the ureter it causes the classic symptoms of renal colic. These include a severe, stabbing pain that occurs in waves that often occur a few minutes apart. Renal colic can continue for hours to days.