A urinary tract infection (UTI) can affect any part of the urinary system, including the kidneys.
When a person refers to a UTI, they are usually talking about a bladder infection or a lower UTI. Bladder infections are the most common type of UTI.
A kidney infection can occur when bacteria, or less often fungi, travel up the urinary tract to infect the kidneys.
Any UTI typically requires professional treatment to prevent serious complications.
From top to bottom, the urinary tract contains the kidneys, the ureters, which are thin tubes connecting the kidneys with the bladder, the bladder, and the urethra — the tube through which urine leaves the body.
The symptoms of a UTI can depend on where the infection occurs — in the lower portion of the urinary tract or the kidneys, for example.
Lower UTI symptoms
A UTI in the lower part of the urinary tract can cause:
- foul-smelling urine
- pain during urination
- an urgent need to urinate but a very low volume of urine
- bloody or cloudy urine
Kidney infection symptoms
If a person does not receive effective treatment for a UTI in the lower tract, the bacteria or fungi can travel upward and infect the kidneys.
If this occurs, a person may experience:
- chills and a fever
- pain in the lower back
- painful urination
The symptoms can vary, however, and some people experience none at all.
Children may be more likely to experience a high fever. Older adults may not experience typical pain or urination issues but may instead experience confusion, problems speaking, or hallucinations.
UTIs are very common in females.
Wiping back to front can push bacteria from the anus toward the urethra, and sexual activity can also move bacteria from the anal area into the urethra.
Once the bacteria reach the bladder they multiply, and the person may then develop UTI symptoms.
Additional UTI risk factors include:
- having diabetes
- not urinating before or after sexual activity
- having multiple or new sexual partners
- having a personal or maternal history of UTIs
- wearing underwear made from synthetic materials
- having experienced menopause
- using diaphragms, douches, spermicides, or unlubricated condoms
- having an especially short distance between the anus and urethra
A kidney infection can result from the same factors that cause any UTI. Most kidney infections occur when an untreated UTI in the bladder transfers to one or both kidneys.
According to the American Kidney Fund, other kidney infection risk factors include:
- blockage of the urinary tract
- a weakened immune system
- catheter drain from the urinary tract
- nerve-related or spinal damage that prevents a person from feeling that their bladder is full
- vesicoureteral reflux, which causes urine to flow back up the urinary tract
Also, a person with an unusually shaped urinary tract may be more prone to lower UTIs and kidney infections if the shape traps bacteria.
It is important to finish the full course of antibiotics as prescribed, even after the symptoms go away. Doing so ensures that the infection is fully treated.
A serious kidney infection may need treatment in a hospital, including intravenous antibiotics and fluids.
If the shape of the urinary tract leads to chronic kidney infections, a doctor may recommend surgery to correct it.
A person can purchase over-the-counter test strips to check for a UTI. If the test or symptoms indicate an infection, contact a doctor.
Typically, the doctor performs a physical examination and asks about the symptoms. If they suspect a bladder infection, they test the person’s urine and prescribe antibiotics to treat the infection.
For a suspected kidney infection, a doctor also orders a urine test to check for the type of bacteria responsible. Once they identify the bacteria, they tend to prescribe antibiotics.
Let a doctor know about any symptoms of a bladder or a kidney infection. Both typically resolve with antibiotics alone.
If a child has a high fever, they need medical attention right away — as do older adults who experience confusion, hallucinations, or new falls. These can all be UTI symptoms.
A person who receives antibiotics usually finds that their UTI symptoms resolve within 1–2 days.
Without treatment, a lower UTI can travel to the kidneys, and if a person does not receive appropriate treatment for a kidney infection, it can enter the bloodstream and become life threatening.
Anyone who experiences frequent bladder or kidney infections should ask a doctor about ways to prevent them.
To reduce the risk of developing a UTI:
- Try to urinate every 2–3 hours.
- Wipe front to back.
- Drink plenty of fluids.
- Try to urinate before and after sexual activity.
- Wear cotton underwear.
- Do not douche.
- Avoid diaphragms and spermicides.
- Change out of wet clothing or bathing suits right away.
- Manage diabetes effectively.
Kidney and bladder infections are both types of UTI. Treatment typically involves a course of antibiotics.
If a person does not receive effective treatment, a UTI can cause serious complications.
Anyone who may have a bladder or kidney infection should contact a doctor. To make a diagnosis, the doctor performs an examination, asks about symptoms, and orders a urine analysis.
As always, it is crucial to complete the full course of antibiotic treatment as directed.