20th August, 20205 min read

How do you get a kidney infection?

Medical reviewer:
Healthily's medical team
Healthily's medical team
Alex Bussey
Alex Bussey
Last reviewed: 21/08/2020
Medically reviewed

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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:

  • pain in your lower back or on 1 side
  • shivering or chills
  • a high temperature and nausea
  • diarrhoea
  • nausea or vomiting
  • loss of your appetite

What causes a kidney infection?

Bladder infections

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.

Blocked urinary tract

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.

Man carrying loo roll walking to loo

Can you get a kidney infection by having sex?

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.

Other causes of a kidney infection

According to the American Kidney Fund, you’re also more likely to develop a kidney infection if you:

  • have a condition that weakens your immune system, such as diabetes or HIV/AIDS
  • use a urinary catheter to drain your bladder
  • take medications that suppress your immune system
  • have a blockage in your urinary tract or a problem with the shape of your urinary tract that makes it harder to pee
  • have a condition called vesicoureteral reflux (VUR), which is when urine flows the wrong way back up the ureters

Is it true that women are more likely to get a kidney infection?

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.

Pregnant woman sitting on a bed cradling her bump (Credit S Hansche)

Am I more likely to get kidney infections if I’m pregnant?

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.

Are kidney infections dangerous?

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.

Key points:

  • kidney infections often start as a bladder infection that moves into the kidneys
  • you have an increased risk of getting a kidney infection if you are sexually active, a woman, pregnant or have a suppressed immune system
  • kidney infections need to be treated using antibiotics
  • kidney infections can cause permanent damage to your kidneys, so it’s important to seek help if you think you might have one
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