Kidney infection


Kidney infection (also known as pyelonephritis) is a type of urinary tract infection (UTI). It is caused by bacteria travelling up the urinary system, infecting the kidney. Symptoms of kidney infection include pain in the back and side, fever, chills, nausea, vomiting, and frequent and urgent urination. Treatment typically includes antibiotics. If left untreated, kidney infection can lead to more serious complications such as kidney scarring and sepsis.


Common symptoms of a kidney infection include:

  • Pain in the lower back, side, or groin
  • Painful or burning sensation when urinating
  • Strong, persistent urge to urinate
  • Cloudy, foul-smelling, or bloody urine
  • Chills and fever
  • Nausea and vomiting
  • Fatigue and general feeling of illness
  • Frequent and small amounts of urine


The most common causes of kidney infections are bacteria from the urinary tract. These bacteria can enter the body through the urethra, the tube that carries urine from the bladder to the outside of the body. Kidney infections can also occur when bacteria from other parts of the body, such as the skin or digestive tract, spread to the urethra and travel up to the kidneys. Other factors that may increase the risk of kidney infection include structural or functional abnormalities of the urinary tract, a weakened immune system, urinary catheters, and kidney stones.

Risk factors

The following are risk factors for developing a kidney infection:

  • Poor hygiene
  • Being sexually active
  • Urinary tract abnormalities
  • A weakened immune system due to chronic conditions such as diabetes or HIV
  • Catheterization for urinary problems
  • Kidney stones
  • Abdominal or pelvic surgery
  • Prolonged use of a urinary catheter
  • Blockage in the urinary tract due to an enlarged prostate or tumors
  • Prolonged use of a bladder or ureteral stent
  • Long-term use of certain medications, such as antibiotics, nonsteroidal anti-inflammatory drugs (NSAIDs), and some cancer treatments
  • Recent urinary tract infection or bladder infection


Kidney infection is typically diagnosed by a combination of a physical exam, urinalysis, blood tests, and sometimes imaging tests such as ultrasound or CT scan. During the physical exam, the doctor will look for any signs or symptoms of a kidney infection, such as abdominal pain or tenderness, fever, nausea, vomiting, chills, or increased urination frequency. Urinalysis is usually done to identify any presence of infection-causing bacteria, abnormalities, or other signs of infection. Blood tests can also be done to measure the levels of certain substances, such as creatinine, that are normally eliminated through the kidneys. If there is suspicion of a kidney infection, imaging tests may be ordered to get a closer look at the kidneys and urinary tract.


The most common subtypes of kidney infection are:

  1. Uncomplicated Urinary Tract Infection (UTI): This is the most common type of kidney infection and is usually caused by a bacterial infection. Symptoms include burning during urination, frequent urination, and cloudy or foul-smelling urine. This type of infection is most typical in women and can be treated with antibiotics.
  2. Complicated Urinary Tract Infection (UTI): This type of infection is more serious than an uncomplicated UTI and may involve the spread of infection to the kidneys, bladder, or ureters. The symptoms can be similar to those of an uncomplicated UTI, but may also include nausea, vomiting, chills, and fever. This type of infection requires more aggressive and longer-term antibiotic treatment.
  3. Acute Pyelonephritis: This type of kidney infection is more serious than other kidney infections and is usually caused by a bacterial infection. Symptoms include back or flank pain, high fever, sudden chills, nausea, and vomiting. Treatment usually involves intravenous antibiotics and hospitalization.
  4. Chronic Pyelonephritis: This is a rare type of kidney infection that can result from recurrent bouts of acute pyelonephritis. Symptoms may include back or flank pain, fatigue, fever, and urinary tract infections. Treatment typically includes long-term antibiotics, lifestyle changes, and dietary changes.
  5. Obstructive Uropathy: This type of kidney infection is caused by a blockage in the urinary tract such as a kidney stone, tumor, or an enlarged prostate. Symptoms may include pain in the side or back, nausea, vomiting, or a high fever. Treatment includes removal of the blockage or obstruction and antibiotics.


The treatment options for kidney infection depend on the severity of the infection, but generally include antibiotics to clear the infection, fluids to replace lost electrolytes, and pain relievers to reduce swelling and pain. Antibiotics are the primary treatment for kidney infections, and they can be taken orally or via injection depending on the infection’s severity. In addition, lifestyle modifications may be necessary, such as increasing fluid intake to help flush out bacteria and reducing physical activity. If necessary, a doctor may prescribe medications to reduce the symptoms of pain and fever associated with kidney infection. Other treatment options may include drainage of the infected area, a course of steroids to reduce inflammation, or a procedure to remove any stones causing the infection.


The most important step to prevent a kidney infection is to practice good hygiene. This includes washing your hands after using the bathroom and before eating. Drinking plenty of fluids, like water, and limiting your intake of alcohol and caffeine can help flush out bacteria from your bladder and kidneys. Urinating after sexual intercourse can also help flush out bacteria that may enter the urinary tract. Older adults and those with a weakened immune system should also take measures to avoid infections, such as drinking plenty of fluids, eating a healthy diet, and getting regular exercise. Other measures include avoiding douching and limiting the use of spermicides. Additionally, it’s also important to seek medical care if you experience symptoms of a kidney infection, such as fever, chills, pain, or burning during urination.

Gender differences?

Yes, there are gender-specific differences in the presentation and management of kidney infections. In general, women experience kidney infections more often than men. Women may also experience more severe symptoms than men and may need more intensive treatments such as antibiotics or hospitalization. Women may also have a higher risk of recurrent infection due to their shorter urethra and proximity to the anus. Kidney infections can be more difficult to treat in women due to anatomical differences and hormonal changes. Additionally, because kidney infections can be a sign of a sexually transmitted infection, women may be more likely to receive screening for these infections and be more aware of the signs and symptoms of kidney infections. However, due to the risk of kidney damage, both men and women should be aware of the signs and symptoms of kidney infections and seek medical attention if they experience any of these.


Nutrition plays an important role in the management of kidney infection. Eating a nutritious diet composed of lean proteins, whole grains, healthy fats, and a variety of fruits and vegetables can help support the body’s natural healing processes and provide the fuel for it to fight the infection. Additionally, certain foods and beverages may help provide relief from painful symptoms. Drinking plenty of fluids, such as water and juices, can help flush the urinary tract and relieve discomfort while also improving kidney function. Including foods high in vitamin C, such as citrus fruits and bell peppers, may also help fight infection. Reducing sodium and limiting foods with high levels of oxalates, such as spinach, may help reduce the risk of further infection. Finally, limiting or avoiding dairy and reducing animal proteins can help control the levels of phosphorus and other toxins in the body, thereby helping to alleviate symptoms of a kidney infection.

Physical Activity

Physical activity can affect kidney infection by helping to reduce stress and promoting a healthy immune system. Regular physical activity can help to reduce hypertension, improve circulation, and promote overall well-being. Increased physical activity has been shown to reduce the risk of developing recurrent urinary tract infections, which can lead to kidney infections. Exercise can also help promote good kidney health by helping to flush the kidneys of toxins, improve kidney function, and increase the body’s ability to absorb nutrients.

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