Regarding the relationship between urinary tract infections, cystitis, pyelonephritis and nephritis people who are not medical students are easily confused. Urinary tract infections are generally defined as infections of the entire urinary tract, including pyelonephritis and cystitis. The general situation is that women are prone to cystitis first for anatomical reasons, when the symptoms are frequent, urgent and painful urination (referred to as urinary tract irritation symptoms); if the condition is not controlled, the infection will further develop and expand retrogradely to the renal pelvis, when the urinary tract infection becomes pyelonephritis. The main manifestation is pain in the kidney area and fever in addition to urinary tract irritation. There is a fundamental difference between nephritis and urinary tract infection, and it is generally easy to confuse pyelonephritis with nephritis. Nephritis is a very complex disease in nephrology and is not directly related to urinary tract infections. The cause of some nephritis is not clear, so it is not necessary to apply antibiotics. Detailed examination is needed to confirm the diagnosis. The most confusing clinical diagnosis is to diagnose nephritis as increased urine routine white blood cells, which is actually incorrect. It may be a simple cystitis, and it will be fine with oral antibiotics for about 1 week, drinking more water and urinating more often. Once urinary tract irritation is accompanied by fever, it may develop into pyelonephritis, at which point intravenous antibiotics are required. What is also misleading is that an increase in urine red blood cells and white blood cells in urinary tract infections can also appear as urine protein, but cannot be diagnosed as nephritis. Therefore, it should not be assumed that the mere presence of protein in the urine means nephritis. When a urinary tract infection occurs, antibiotics are necessary. The initial choice of antibiotics is based mainly on clinical experience. Because the most common type of urinary tract infection is E. coli, antibiotics that target E. coli are applied. Quinolones are commonly used clinically, such as haloperidol capsules and ofloxacin capsules. Cephalosporin antibiotics can also be applied. Penicillin is generally ineffective is not the best choice. Some serious infections or recurrent urinary tract infections, bacteria may be resistant to drugs, then you need to carry out urine bacterial culture and drug sensitivity test, according to the bacterial species and drug sensitivity test scientific selection of antibiotics. Usually, we treat urinary tract infections easily repeatedly because of insufficient time with antibiotics. Often, the medication is stopped as soon as the symptoms get better. This can make some bacteria are not completely killed and temporarily inhibited. Once the body’s resistance decreases the inhibited bacteria immediately have active reproduction. Therefore, antibiotics are applied until the symptoms are relieved and the routine urine test is negative for 3 consecutive times. Urinary tract infections are necessary to drink more water. Some patients have urinary tract infections with painful urination, so they are afraid to drink water and reduce the number of urination is not right. Only more urination can flush the infected urinary tract and promote the recovery of urinary tract infection as soon as possible.