The urine is purple, possible causes: 1, due to the use of drug staining, such as the use of salicylic acid, taking aminoglutethimide, or intravenous methylene blue, the use of melanoma, etc., can appear urine is purple situation, usually due to drug staining, rather than disease conditions, after stopping the relevant drugs, the urine color can return to normal. 2, seen in long-term indwelling catheter, or indwelling cystostomy tube, combined with Patients with chronic infections can develop purple urine, staining the urine bag purple, clinically known as purple urine bag syndrome. 3, the presence of infection, the presence of a large number of bacteria in the urine, after eating tryptophan decomposition in the intestine to form indole, absorbed by the intestine into the liver to form indole sulfate, excreted through the urine, indole sulfate in the urine under the action of bacteria, decomposition to produce indocyanine and indocyanine red, the two mixed on The urine can appear to be purple.