Copper, phenacetin, phenol poisoning or medications that cause excessive L-dopa or melanin excretion will cause black urine.. Ingestion of large amounts of rhubarb, fava beans, or aloe can cause dark brownish black urine. Many medications(see reference) may cause brown or brown-black urine.
Black urine may be associated with the following disease states: Melanoma may cause melanin and melanogen excretion and will darken standing urine.. Alcaptonia, a rare hereditary disease, may cause urine to turn dark after being exposed to the air over a period of time. Urinary tyrosinosis will also cause urine to be brown-black in color. In porphyria cutanea tarda, the urine will appear reddish brown in natural light but fluoresces pink under ultraviolet light.
