The most common cause of red urine in men is hematuria, but red urine can also occur after taking certain medications or fruits with colors. In this case, you need to go to the hospital for a routine urine test to see if it is sarcoid hematuria. If it is determined to be carnal hematuria, you can perform urine red blood cell morphology examination to see the red blood cells. If the proportion of intact red blood cells is high, it is usually urological disease, such as tumor, stone, inflammation, etc.; if the proportion of broken red blood cells is high, it is usually urological disease, such as glomerulonephritis, nephrotic syndrome, etc. In serious cases, a kidney puncture biopsy is needed. However, because the male penis is longer, leading to the situation of easy trauma, there will also be the case of hematuria, should be clear medical history except the possibility of injury.