Because pitaya contains anthocyanins, if eaten beyond the upper limit of human catabolism, it will be excreted from urine, and urine will turn red, but it will generally disappear after 1-2 days, up to 3 days after stopping eating. If the urine is still red after stopping eating, you should go to the hospital for examination, because common hematuria is also red, such as ureteral calculi, bladder calculi and kidney calculi. For example, long objects in the urinary system, such as cancerous lesions, can also cause hematuria; There are also glomerulonephritis, IgA nephropathy, and sometimes paroxysmal hematuria and gross hematuria; There are also diseases such as basement membrane nephropathy and urinary tract infection, which will lead to red urine. These must be diagnosed in the hospital, especially to avoid misdiagnosis.