Normal urine is clear and has a straw-yellow color. The color of the urine, however, can vary when foods of certain types are consumed or when certain medications are taken. Some substances that can change the color of the urine and potentially lead to darker urine are carotene, food colorings, beets, blackberries, laxatives, B complex vitamins, and drugs such as Pyridium. The urine may also appear darker when there is bleeding into the urine, and the numerous causes of bloody urine (for example, infections, stones, cancer, trauma, kidney diseases) can all contribute to a darker appearance of the urine. In the presence of a urinary tract infection, the urine can also be cloudy and may appear darker. Jaundice, which is characterized by abnormally high levels of bilirubin in the bloodstream, is caused by diseases of the liver or obstructions to the flow of bile pigment (by diseases of the head of the pancreas, diseases of the bile ducts, or the presence of stones in the bile duct) and can also be associated with darkening of the urine. It is wise to consult a health care practitioner about any change in urine appearance that is not related to diet and/or medications.

Source: http://www.rxlist.com