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We can't say exactly what will happen if you have a kidney infection. Some people get better quickly with treatment. But these infections can be serious. Some people need treatment in the hospital.

What will happen to you depends on several things. These include:^{1 2}

• How bad your infection is
• How old you are
• Whether you have other health problems
• Whether you get the right medication
• Whether treatment works for you.

If your doctor thinks you have a kidney infection, you'll probably need to give a urine sample. This can be tested to find out what kind of bacteria are causing your symptoms. Your doctor can then prescribe the type of drug that's best at killing those bacteria. To read more about giving a urine sample, see What are the symptoms of a kidney infection?

Your treatment also depends on whether your kidney infection is complicated or uncomplicated. If your infection is complicated, it means it's more serious for some reason. You might have another medical condition that makes your infection worse, for example.

If you have an uncomplicated infection, you'll usually be treated at home. If you get the right treatment, you should be feeling much better within a few days. You'll probably be completely cured after two weeks.³

About 9 in 10 people with an uncomplicated infection can be treated at home. Your doctor needs to make sure that you:¹

• Can take drugs as pills (you don't need to be given drugs as an intravenous infusion). For example, if you're vomiting a lot you might not be able to take pills.
• Have good support at home.

If you're treated at home, you'll probably be advised to take acetaminophen (brand name Tylenol) to reduce pain and fever. To read more, see Painkillers for people with a kidney infection. You'll also be advised to drink plenty of fluids.

You'll need to see a doctor for checkups. Let the doctor know if you are not getting better, or are getting worse, after a few days.⁴

You'll need to be treated in the hospital if:⁵

• You're feeling sick to the stomach a lot and can't keep fluids down
• You have signs of sepsis. Sepsis is a dangerous complication where bacteria get into your bloodstream.
• Your doctor isn't sure your symptoms are caused by a kidney infection
• Your urinary tract is blocked. Your urinary tract includes your kidneys, bladder and the tubes that carry urine.

You may need to go to the hospital if you:

• Are over 60
• Are pregnant
• Have another health problem that affects your urinary tract
• Are no better after three days, or you're getting worse
• Have an immune system that's been weakened and can't fight disease as well as it should. This could be because of diabetes, cancer or an organ transplant.
• Think you would find it difficult to get to follow-up appointments
• Don't have good support at home.

If you're treated in the hospital, you'll probably be given antibiotics as an intravenous infusion (an IV). Drugs given as an IV work quickly because they go straight into your bloodstream. Once you're feeling better, usually after two or three days, you'll probably move on to antibiotic pills.⁶

Most people need to take antibiotics for about two weeks. But if you have a mild infection, taking them for a week may be enough.⁶ If you have a complicated kidney infection, you may need to take antibiotics for as long as three weeks.² It's very important to finish the course of pills, even if you feel better before you've finished taking them.

You should have another urine test one or two weeks after you finish taking antibiotics. This is to make sure that you're not infected any more.¹

Sometimes antibiotic treatment doesn't work. This may happen if:¹

• The bacteria that are causing the infection have become resistant to the particular drug you've been given. This means the bacteria have changed and can't be killed by that drug. You'll need to be given another drug.
• You have a kidney stone. You may need surgery to remove it.

Although most people get better completely with treatment, some go on to have complications. These can include:⁷

• A build-up of pus in your kidney, called an abscess. You may need surgery to remove the pus.
• Sepsis. This is a serious illness caused by bacteria getting into your bloodstream. The bacteria make poisonous chemicals which can make you very sick. If you get sepsis, you'll need intensive care in the hospital and antibiotics given by an IV.
• Sudden kidney failure. This is when your kidneys stop working. It's a serious problem, and you'll need intensive care in the hospital, but it usually gets better. While your kidneys aren't working, you may need a treatment called dialysis. Dialysis uses a machine to filter your blood and remove waste and fluids in the same way your kidneys would.

Some people get repeated kidney infections. This can lead to scarring and permanent damage to the kidney.⁸ These attacks usually happen less often with time, but your doctor may recommend that you take a small dose of an antibiotic every day to prevent infections.⁴

It's rare for a kidney infection to be bad enough to die from, but it can happen. Men are more likely to die from a kidney infection than women. About 16 men die for every 1,000 who have a kidney infection. For women, it's only about 7 in 1,000.⁹

This information is for educational use only, and is not a substitute for prompt professional medical advice. Readers should always consult a physician or other professional for advice and treatment. ©BMJ Publishing Group Limited 2008. All rights reserved.