Kidney infection – what you need to know

Find out why women are more likely to get this type of urinary tract infection (UTI), how long it lasts, and how it's treated.

Kidney infections and women 

Kidney infection vs UTI

What causes a kidney infection?

What are the symptoms?

Is anyone more at risk of kidney infection?

What does a kidney infection feel like?

When to see a doctor

How to get rid of a kidney infection

Preventing kidney infections

Is it ever serious?

Getting pain in your side, lower back or around your genitals? A fever along with feeling really tired and weak, or nausea and/or vomiting? It could be a kidney infection – find out how to get it sorted, and stop it coming back.

## Kidney infections and women 

Kidney infections are much more common in women: every year in the US, there are about 15 to 17 cases per 10,000 women, compared with just 3 to 4 cases for every 10,000 men. Similarly, in the UK, women are about 6 times more likely to get one than men.

“A kidney infection can make you feel really sick,” says [Dr Ann Nainan](/team/medical/dr-ann-nainan), family doctor and Healthily expert. “But the good news is that if you get it diagnosed and treated quickly with antibiotics, it will clear up and is unlikely to cause you any serious health problems.”


## Kidney infection vs UTI

So, what exactly is a kidney infection?

- it’s a type of [urinary tract infection (UTI)](/health-library/conditions/urinary-tract-infection-adults) – many people think of UTIs as something that affects your bladder and pee tube (urethra), in the lower urinary tract. But you can also get a bacterial infection in your upper urinary tract, including your kidneys
- the medical name for a kidney infection is ‘pyelonephritis’ 


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## What causes a kidney infection?

Here’s what you need to know: 

- it’s usually caused by [cystitis](/health-library/conditions/cystitis) – a common bladder infection that happens when bacteria from your bottom (anus) get into your pee tube (urethra) 
- this transfer of bacteria can happen during sex, or if you don’t wipe from front to back when you poop
- the bacteria can then travel from your urethra, through your bladder (where the infection is called cystitis) and on into 1 or both of your kidneys
- having cystitis doesn’t mean you’ll get a kidney infection – only 1 in 30 cases of a lower UTI leads to kidney infection, which means that 29 in 30 don’t 
- it can be more likely if you get cystitis often, or if you have a structural problem in your urinary tract, such as [kidney stones](/health-library/conditions/kidney-stones)
- it’s also possible to get a kidney infection without having cystitis – if you have kidney stones, diabetes or a weakened immune system, for example 
- in about 5% of cases, the bacteria can get into your kidneys from another part of your body via your bloodstream


## What are the symptoms?

“Many of the symptoms of kidney infection overlap with the symptoms of lower urinary tract infections,” says Dr Ann. 

“But 3 symptoms – pain in your side/lower back, fever, plus nausea and vomiting – happen more often in people with kidney infection than those with a lower UTI, such as cystitis. So these symptoms can be the telltale signs that differentiate a kidney infection.”

Kidney infection symptoms can come on suddenly, within a few hours. You can get:

- shivering or chills
- fever 
- pain in your side, lower back or around your genitals
- loss of appetite
- nausea
- vomiting
- feeling very weak or tired
- diarrhea

You might have other symptoms if you also have cystitis, including:

- pain or burning when you pee
- needing to pee suddenly or more often than usual 
- blood in your pee
- smelly or cloudy pee
- pain low down in your stomach
- pain in your genitals

Worried you could have a kidney infection? Use our [Smart Symptom Checker](/symptom-checker) to help you work out your best next steps. 

## Is anyone more at risk of kidney infection?

You’re more likely to get a kidney infection if:

- __you’re a woman__ – “kidney infections are more common in women because your urethra is shorter than a man’s, plus it’s closer to your anus, which makes it easier for bacteria to reach your kidneys,” says Dr Ann
- __you have sex frequently__ – “this is because bacteria can be transferred to your genitals during sex, from where it can potentially travel up to your kidneys,” says Dr Ann
- __you’re pregnant__ – “pregnancy causes hormonal and physical changes – such as pressure on your urinary tract from your growing baby – which can make a kidney infection more likely,” says Dr Ann
- __you have a catheter__ – this is a tube that drains pee from your bladder, which you might need after having surgery or if you’re confined to bed
- __you have certain health conditions__ – you can be more susceptible to kidney infections if you have:
  - a condition that weakens your immune system, such as [diabetes](/health-library/conditions/diabetes) or [HIV](/health-library/conditions/hiv)
  - a urinary tract blockage – from kidney stones, a narrowed urethra or (in men) an [enlarged prostate gland](/health-library). A blockage can slow down your pee or make it harder to fully empty your bladder
  - damage to the nerves around your bladder
  - a condition called ‘vesicoureteral reflux’, which causes your pee to flow the wrong way



## What does a kidney infection feel like?

Here’s how women describe their experiences of a kidney infection: 

### “I rolled out of bed, vomited, and buckled over from blinding pain”

Miranda, 24, explains that a UTI turned into a painful kidney infection. “I woke up at 3am feeling like someone had kidney-punched my guts,” she says. “I rolled out of bed, vomited, and buckled over from blinding pain in my lower back. I called a friend to take me to the emergency room. The doctors did a urine test and diagnosed me with a kidney infection from leaving my UTI untreated for too long.”

### “I was shivering uncontrollably”

Cherry, 30, was maid of honor at her best friend’s wedding when she started feeling so sick she had to go to the emergency room, where she was diagnosed with a kidney infection. “I’d been busy working, so I was a bit run-down, and thought I was developing a migraine. I was taking ibuprofen, but nothing was working,” she says. “I could barely focus on talking, let alone do anything useful for the bride. I didn’t touch any food. I was shivering uncontrollably and obviously had a fever.”

### “The worst pain of my life”

Madi was traveling in Europe with her boyfriend when her UTI developed into a kidney infection. She describes it as “the worst pain of my life… a shooting pain, like, up my back.” She went to the emergency room in Paris, where she was given antibiotics and pain medication. Following her experience, she says “just go to the doctor” if you think you may have a kidney infection.


Watch this video from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

## When to see a doctor

See your doctor if you:
- feel feverish and have pain in your back, sides or around your genitals that doesn’t go away 
- have symptoms of a UTI that haven’t gotten better after a few days
- have blood in your pee

You should see a doctor urgently if you think your child has a UTI, even if it’s just cystitis. 

### Kidney infection – when to go to hospital? 

Go to the emergency room if you have a kidney infection and signs of [dehydration](/health-library/conditions/dehydration) or [sepsis (blood poisoning)](/health-library/conditions/blood-poisoning), which include:

- fever
- chills
- rapid breathing and heart rate
- being unable to swallow or keep fluids down
- rash 
- confusion
- drowsiness

### How is a kidney infection diagnosed?

The tests you’ll have when you see your doctor will depend on your symptoms and medical history, but can include:

- __questions__ – including about when your symptoms began and what they feel like, plus your general health history
- __physical exam__ – your doctor may check your abdomen for pain and/or tenderness
- __urinalysis__ – when a sample of your pee is tested for signs of infection
- __urine culture__ – when bacteria from your urine sample are grown in a laboratory to look at the numbers and types of bacteria
- __[blood tests](/health-library/medical-exams/blood-tests)__ – your doctor might order these to look for increased white blood cells (which suggests infection), bacteria in your blood, or kidney damage
- __[CT scan](/health-library/medical-exams/ct-scan) or [ultrasound scan](/health-library/conditions/memory-loss/#ultrasound-scan)__ – these aren’t normally needed to diagnose kidney infection, but can be used to check for problems with your urinary tract. They may be used if:
  - your symptoms don’t respond to [antibiotics](/health-library/conditions/kidney-infection/#treatment)
  - your symptoms suddenly get worse
  - you have symptoms that aren't usually associated with a kidney infection
  - you’re prone to kidney infection complications


## How to get rid of a kidney infection

### Treatment from your doctor

“You’ll always need to take [antibiotics](/health-library/drugs/antibiotics-penicillins) prescribed by your doctor to clear a kidney infection,” says Dr Ann. “A lower UTI, such as cystitis, can sometimes go away on its own, but with a kidney infection you always need treatment straight away – if it’s left untreated, it can cause serious complications.

“It’s also really important to take all your medication as prescribed, even if you start feeling better, because the infection might come back if you stop the medication too soon.”

Most people can take a course of antibiotics at home, but there are times when you might need to be treated in hospital. This includes if:

- you’re severely dehydrated
- you can’t swallow or keep down fluids or medicines
- you’re over 65
- you’re pregnant and have a fever
- your symptoms don’t improve within 24 hours of starting antibiotics
- you have a weakened immune system
- you have another health condition, such as diabetes, or something inside your urinary tract, such as kidney stones or a catheter
- you have symptoms that suggest you might have blood poisoning

Children are usually treated in hospital for kidney infection, too. 

### Self-care help

While your kidney infection medication is kicking in, there are things you can do to help yourself feel better, including: 

- taking [acetaminophen (paracetamol)](/health-library/drugs/painkillers-paracetamol) to help ease pain. Ibuprofen isn’t usually recommended, because it might increase your risk of more kidney problems – always talk to your doctor first
- drinking plenty of water – this helps to flush out bacteria from your kidneys. Aim for enough so that your pee is pale colored, almost like water. And avoid alcohol and caffeine
- taking time to rest – having a kidney infection can be exhausting, so don’t feel bad about missing work and taking it easy in bed or on your couch. “It’s a good idea to avoid any strenuous exercise – you probably won’t feel up to it anyway,” says Dr Ann. “As you start to feel better, you could do some gentle yoga or go for short walks. Listen to your body”
- avoiding ‘hovering’ over the toilet seat when you go to the bathroom – as this can mean your bladder doesn’t empty properly

### How long does a kidney infection last?

“You should begin to feel better within 2 to 3 days of starting your antibiotic treatment,” says Dr Ann. “But your total kidney infection recovery time is likely to be longer. For most people, it can take up to 2 weeks to feel fully fit, healthy and like yourself again.”


## Preventing kidney infections

“There are lots of things you can do to reduce your chance of getting a kidney infection in the first place,” says Dr Ann. These include:

- drinking plenty of fluids to flush out bacteria from your urethra
- not delaying peeing if you need to go – bacteria are more likely to grow when pee stays in your bladder for too long
- always wiping from front to back after pooping – this moves bacteria away from the opening of your pee tube
- peeing after having sex – this may help to flush out any bacteria from your urethra 
- being contraception-wise – avoid using a [diaphragm](/health-library) or [condoms](/health-library) coated in spermicide, as it’s thought that spermicide can increase your risk of UTIs
- keeping [constipation](/health-library/conditions/constipation) at bay – it can increase your chances of getting a UTI, because if poop stays in your body it can put pressure on, or block, your bladder. So always treat [constipation quickly](/health-library/conditions/constipation/#treatment-from-the-pharmacy)


## Is it ever serious?

Most people recover without problems from a kidney infection. But possible complications include:

- kidney abscess – rare but serious, this is when pus forms in the tissue of your kidney(s). It’s potentially fatal, because the bacteria in the abscess can spread to other parts of your body such as your bloodstream or lungs 
- a severe infection of the kidneys called emphysematous pyelonephritis 
- sepsis 
- kidney scarring
- kidney failure


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References

 Christina Quaine

Susie Parker

Dr Flora Kaminsky

Dr Sarnia Ward

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Women are much more likely than men to get kidney infections. Learn the signs, so you can get treatment when you need it.