Can cranberry supplements cause dark urine?

Maybe: ...To me color is not that important most of the time... However cranberries are beneficial in preventing urinary tract infections... So if one can get the beneficial effect without the added sugar - great ........

Cranberry: Possible but fluids drank also important factor.

Lots of causes. : Dark can be from dehydration, pignents from e.g. beets, bile obstruction (jaundice), blood, other. Not aware that cranberry supplements by themsrlves would do so. Many people take them to prevent, or treat UTI (doesn't work for that). UTI can cause blood in urine (looks dark); so can blood from kidney stones (risk of cranberry supplements-oxalate content). Check with your doc.