This page summarises publicly available NHS information for educational purposes only. It is not medical advice or a diagnosis. Always consult a qualified healthcare professional.
What is kidney infection?
A kidney infection (pyelonephritis) is a urinary tract infection that has spread to one or both kidneys. It usually causes fever, back or side pain, feeling very unwell, and sometimes symptoms like pain when peeing or blood in urine. Kidney infections need prompt antibiotic treatment — see a GP the same day if you suspect one.
When NHS resources suggest seeing a GP
- Pain, burning or stinging when you pee.
- Needing to pee more often and urgently than usual.
- Pee that's dark or cloudy.
- Kidney infection symptoms that have not gone away after treatment with antibiotics.
- You think you or your child may have a kidney infection and.
- Have a very high temperature, or feel hot, cold or shivery.
Self-care information from NHS
- There are some things you can try to ease kidney infection symptoms while you're having treatment. They can also help prevent a kidney infection coming back.
- Rest – it can take up to 2 weeks before you feel able to return to work.
- Drink lots of fluids, such as water or squash – take small sips if you feel sick.
- Take paracetamol to reduce a high temperature and relieve pain.
- Give your child liquid paracetamol for children if they're distressed or uncomfortable – check the packaging or leaflet to make sure the medicine is suitable for your child, or speak to a pharmacist or GP if you're not sure.
- Ask your doctor how much fluid you can drink if you have kidney problems.
- Always try to fully empty your bladder when you pee.
- Do not take ibuprofen unless advised by a doctor – it may increase your risk of further kidney problems.
Common questions
How do I know if it's a kidney infection?
Signs include fever, chills, pain in the side or lower back (usually one side), nausea or vomiting, and feeling very unwell. These are often combined with typical UTI symptoms — pain when peeing, cloudy or smelly urine, and frequent urination.
How long does a kidney infection take to clear?
With antibiotics, symptoms usually improve within 48 to 72 hours and the infection clears in 10 to 14 days. Most people need a 7 to 14 day antibiotic course. Severe cases may need hospital admission for IV antibiotics.
When is a kidney infection an emergency?
Call 999 or go to A&E if you feel very confused, have severe pain, can't keep fluids down, have a very high fever, or your skin is mottled or very cold — these can signal sepsis, a life-threatening complication.
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This page is for informational and educational purposes only. It does not constitute medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional about your individual situation. NorMed organises publicly available NHS information and is not affiliated with the NHS.