The first is urinary tract infection. When bacterial or fungal infection occurs, the urine will be filled with a large number of white blood cells, pus cells, and some bacterial metabolites shed epithelium, etc., which can appear smelly, accompanied by cloudy urine, accompanied by frequent urination, urinary urgency, painful urination, etc. It is necessary to carry out urine culture examination and give anti-infection treatment after the diagnosis is confirmed. Second, if you eat special smelling ingredients, such as onion, garlic or durian, it can cause a transient odor of urine. The odor can disappear or diminish after stopping the food in question and drinking plenty of water. Thirdly, when there is an extremely concentrated urine, it can appear to smell more foul, such as patients with urinary retention, or patients who drink less water and sweat more. When the urine is concentrated, some components in the urine decompose or evaporate, causing a foul odor. Fourth, if you drink a large amount of meat diet for a long time and seldom have a vegetarian diet, you can have more smelly urine. The meat diet can cause the urine to be acidic, and the protein content in the urine is relatively increased, which can lead to the decomposition of proteins and the production of ammonia, which can cause the urine to smell bad.