Acute pyelonephritis is a disease that occurs due to severe kidney infection. The infection starts through the lower urinary tract infection (UTI) and spreads through the urethra, where the bacteria multiplies. The bacteria travels through the ureters and reaches the kidney. Moreover, the bacteria can reach the kidney through the blood stream. The disease occurs mostly in women due to shorter urethra as compared to men. Acute pyelonephritis is caused due to bacteria such as E.coli, Enterobactor, Pseudomonas and many more. Acute pyelonephritis is diagnosed with urine tests, imaging and radioactive imaging. The urine tests would check for the bacteria, pus cells and concentration while imaging tests such as ultrasound will diagnose the obstructions in the urinary tracts. The patient may have a significant impact if the disease is not treated on time. The disease spreads and establishes itself very quickly with bladder inflammation, chills, fever, urinary frequency and urgency. Acute pyelonephritis is treated with broad spectrum antibiotics such as levofloxacin, ciprofloxacin and ampicillin. However, in severe cases the drugs are ineffective and the patient has to be hospitalized. Moreover, due to the increased levels of progesterone and increased pressure on the uterus, pregnant women are also prone to acute pyelonephritis. Acute pyelonephritis can be prevented by drinking plenty of water, which will remove the bacteria from the body in the form of urine.