Transient hematuria can be caused by pollen, chemical or drug allergies. Transient hematuria, or even carnal hematuria, can occur after strenuous exercise, and can occasionally occur with viral infections (e.g., colds) and is usually of no importance. Only repeated tests for true hematuria should be taken seriously and further tests should be performed. After strenuous exercise, transient hematuria, or even carnal hematuria, may occur. Occasionally, hematuria can occur with viral infections (e.g., flu) and is usually not significant. Only repeated tests for true hematuria should be taken seriously and further tests should be performed. There are many causes of hematuria: 1. Systemic diseases Blood diseases (leukemia), infectious diseases (such as epidemic hemorrhagic fever), cardiovascular diseases (such as congestive heart failure), connective tissue diseases (systemic lupus erythematosus), drugs (sulfonamides, salicylates and anticoagulants), etc. 2. 2, diseases of organs adjacent to the urinary tract, such as: acute appendicitis, acute or chronic pelvic inflammatory disease, inflammation of the colon or rectal diverticulum, malignant tumors, and other diseases invade or stimulate the urinary tract, sometimes can produce hematuria, but not commonly. 3, kidney and urinary tract diseases such as: various types of nephritis, kidney basement membrane disease, pyelonephritis, polycystic kidney, renal prolapse, urinary tract stones, tuberculosis, tumors and vascular lesions, trauma, etc. 4, other factors and certain poisons (phenol, carbon monoxide, chloroform, snake venom), drugs (sulfonamide, quinine), crush injuries, burns, malaria, wrong type of blood transfusion and other causes of hemoglobinuria or myoglobinuria. While transient hematuria can be caused by pollen, chemical or drug allergies, it can also occur after strenuous exercise or viral infections.