The symptoms of a kidney infection usually develop quite quickly over a few hours or days.

Common symptoms include:

• pain and discomfort in your side, lower back or around your genitals
• high temperature – 38C (100.4F) or above; it may reach 39.5C (103.1F)
• shivering or chills
• feeling very weak or tired
• loss of appetite
• feeling sick or being sick
• diarrhoea

You may have other symptoms if you also have a urinary tract infection (UTI) such as cystitis.

These additional symptoms may include:

• pain or a burning sensation when peeing
• need to pee suddenly or more often than usual
• blood in your pee
• smelly or cloudy pee
• pain in your lower tummy
• pain in your genitals

In older people, a kidney infection may cause confusion.

Symptoms in children

Children with a kidney infection may have the following symptoms:

• smelly pee
• blood in their pee
• wetting the bed
• a high temperature and feeling unwell (they may complain of tummy ache)
• vomiting and/or not feeding well

A child younger than 2 with a kidney infection may only have a high temperature, without any other obvious symptoms.

When to see your GP

See your GP if you feel feverish and you have pain in your tummy, lower back or genitals that won't go away.

You should also see a GP if you have symptoms of a UTI that haven't improved after a few days, or if you have blood in your pee.

Contact your GP immediately if you think your child may have a kidney infection.

Kidney infections require prompt treatment with antibiotics.

Most people with a kidney infection can be treated at home with a course of antibiotics, and paracetamol if needed.

See your GP if you feel feverish and have pain in your tummy, lower back or genitals that won't go away.

You should also see a GP if you have symptoms of a UTI that haven't improved after a few days or if you have blood in your pee.

If you think your child has a UTI, even if it's just cystitis, make sure you see a GP or go to an out-of-hours emergency service.

Medication

Antibiotics

If you're being treated at home, you'll usually be prescribed a course of antibiotic tablets or capsules that lasts between 7 and 14 days.

Usually, you'll start to feel better quite soon after treatment starts and should feel completely better after about 2 weeks.

If your symptoms show no sign of improvement 24 hours after treatment starts, contact your GP for advice.

Painkillers

Taking a painkiller such as paracetamol should help relieve symptoms of pain and a high temperature.

However, anti-inflammatory painkillers (NSAIDs) such as ibuprofen aren't normally recommended for a kidney infection – they may increase the risk of further kidney problems so shouldn't be taken unless advised by a doctor. A doctor may only prescribe these in certain circumstances.

Things you can try yourself

If you have a kidney infection, try not to "hover" over the toilet seat when you go to the loo because it can result in your bladder not being fully emptied.

It's also important for most people with a kidney infection to drink plenty of fluids (water is best) because this will help to flush out the bacteria from your kidneys. Aim to drink enough so that you're frequently passing pale-coloured urine.

If you have kidney failure, get advice from your doctor on how much to drink.

Make sure you get plenty of rest. A kidney infection can be physically draining, even if you're normally healthy and strong. It may take up to 2 weeks before you're fit enough to return to work.

Treatment at hospital

Your GP may refer you to hospital if you have an underlying problem that makes you vulnerable to kidney infections.

It's standard practice to further investigate all men with a kidney infection simply because the condition is much rarer in men. Women don't tend to be referred unless they've had 2 or more kidney infections.

Most children with a kidney infection will be treated in hospital.

Hospital treatment may also be needed if:

• you're severely dehydrated
• you're unable to swallow or keep down any fluids or medications
• you have additional symptoms that suggest you may have blood poisoning, such as a rapid heartbeat and losing consciousness
• you're pregnant and you also have a high temperature
• you're particularly frail and your general health is poor
• your symptoms fail to improve within 24 hours of starting treatment with antibiotics
• you have a weakened immune system
• you have something inside your urinary tract, such as a kidney stone or a urinary catheter
• you have diabetes
• you're over the age of 65
• you have an underlying condition that affects the way your kidneys work, such as polycystic kidney disease or chronic kidney disease

If you're admitted to hospital with a kidney infection, you'll probably be attached to a drip so you can be given fluids to help keep you hydrated. Antibiotics can also be given through the drip.

You'll have regular blood and urine tests to monitor your health and how effectively the antibiotics are fighting off the infection.

Most people respond well to treatment. As long as there are no complications, you should typically be well enough to leave hospital in 3 to 7 days.

Treatment will usually switch to tablets or capsules after you stop receiving antibiotics through a drip.

You may need further investigations if you get more than one kidney infection. Your GP or hospital specialist would arrange these tests for you.