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Written by: Alex Bussey
Edited by: Mike Martin
Reviewed by the Your.MD medical team
Kidney infections (pyelonephritis) are quite rare, but they can be very unpleasant.
An untreated kidney infection can also cause permanent damage to your kidneys, so it’s important to know the symptoms and understand how a kidney infection develops.
Common symptoms include:
Experts think that most kidney infections start as a bladder infection (sometimes called a urinary tract infection or UTI) that moves up into your kidneys.
These infections normally develop when bacteria from your colon spread to your genital area, and then move up into your bladder through your urethra.
It’s thought that about 90% of urinary tract infections are caused by a type of bacteria called Escherichia coli (E. coli) that normally lives in your colon.
Once they are in your bladder, harmful bacteria like E. coli can move into your kidneys via a pair of tubes called the ureters, which is how most kidney infections develop.
You can also get a kidney infection if your urinary tract gets blocked by something like a kidney stone or an enlarged prostate gland.
This is because these blockages often trap urine, and bacteria can grow in the trapped pee before travelling up to your kidneys and causing an infection.
Being sexually active can increase your chances of developing a kidney infection.
This is because sexual intercourse can spread E. coli and other bacteria from the colon to the genital area, allowing them to move up into your urethra and infect your urinary tract.
According to the American Kidney Fund, you’re also more likely to develop a kidney infection if you:
Yes. Women are more likely to get a kidney infection than men. There are 2 main reasons for this.
Firstly, a woman’s urethra is closer to her anus, which makes it easier for bacteria like E.coli to move from one to the other.
Secondly, women have a much shorter urethra than men, which means that bacteria and other germs find it much easier to move up into the bladder and cause an infection.
The skin around a man’s urethra is also drier than the skin around a woman’s, which means that harmful bacteria find it harder to grow there.
However, men can still get kidney infections, especially if they have an infected prostate gland (prostatitis). This is because the bacteria that cause prostatitis often spread to the kidneys.
According to the Republic of Ireland’s Department of Public Health, 90% of men who have kidney infections also have prostatitis.
Pregnancy can increase your chances of developing a kidney infection.
This is because pregnancy enlarges your uterus, and puts a lot of pressure on the tubes that carry pee from your kidneys to your bladder (the ureters).
This can stop you from getting rid of all of your pee, and allows dangerous bacteria to grow close to your kidneys.
Pregnancy can also reduce the muscle movements that push urine down to the kidneys, which can lead to urine moving back up your ureters and into the kidneys.
Kidney infections can make you feel very ill, but they can be treated with antibiotics and most people make a full recovery.
But it’s important to get help from a doctor as soon as you can, because an untreated infection can cause permanent damage to your kidneys.
You may need to go to hospital if you have a kidney infection and you’re pregnant or have a long-term health condition.
Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.