The red color of urine may be caused by non-disease factors such as strenuous exercise, or it may be caused by diseases such as urinary tract infections, thrombocytopenic purpura, infective endocarditis and so on. 1. Non-disease factors: people who usually exercise less, a sudden large amount of exercise will cause the urine to be red. The use of drugs such as indomethacin and cyclophosphamide can also cause this symptom. Consumption of large quantities of dragon fruit, will also appear in the red urine 2. Diseases (1) Urological diseases: primary glomerular disease, allergic purpura, pyelonephritis, urethral stones, renal artery thrombosis and other diseases, patients will hematuria. (2) Systemic diseases: thrombocytopenic purpura, infective endocarditis, sepsis, hypertension, diabetic nephropathy, etc., patients can also have hematuria. There are many causes of red urine, and patients are advised to go to the hospital in time to find out the cause and get timely treatment.