On this page
Dr. Chrysoula I. Liakou MD, PhD
- Treated online: Assessment online. A doctor can judge whether your symptoms could be a kidney infection and how urgently you need to be seen; the urine test, the examination and the antibiotics are in person.
- What it is: a urinary tract infection that has spread to one or both kidneys, usually from the bladder. It can be serious if it is not treated.
- Typical signs: a high temperature, pain in the lower back or side, and feeling or being sick, often with the burning and frequent peeing of cystitis.
- Recovery: antibiotic tablets for 7 to 14 days treat most kidney infections, and most people feel better around 2 weeks after starting treatment.
- Emergency: call 112 for confusion, drowsiness or slurred speech, very fast breathing, blue, pale or blotchy skin, or no longer passing urine.
Do not book a video appointment if you are confused, drowsy or have slurred speech, are breathing very fast, have blue, pale or blotchy skin, or have stopped passing urine. Call 112 or go to an emergency department, and do not drive yourself. A high temperature with pain in your back or side, or urinary symptoms with a temperature in pregnancy, needs an urgent in-person assessment rather than a video call.
Can an online doctor help with a kidney infection?
No, a kidney infection cannot be treated online: a urine sample needs to go for culture before antibiotics start, and a doctor needs to examine you to judge how unwell you are. What a doctor by video can do is go through your symptoms, tell you plainly whether they could mean a kidney infection and how quickly you need to be seen, consider the other causes, and help after treatment, for example if symptoms are slow to improve or keep coming back. If you already think you have a kidney infection, get seen in person rather than waiting for a video call.
How an online consultation helps with a possible kidney infection
- Urgency made clear: Whether you need an emergency department now, an urgent appointment in person, or treatment for cystitis.
- Other causes considered: Kidney stones, pelvic inflammatory disease or a bladder infection alone can feel similar.
- Help after treatment: What to expect while you recover, and when symptoms that are not improving need a review.
- Infections that keep coming back: Which tests are worth arranging after repeated urine infections or more than one kidney infection.
What the doctor checks in an online assessment of a possible kidney infection
The doctor asks about the signs of sepsis first, then about the infection itself. The doctor asks about:
- Warning signs: confusion, drowsiness, slurred speech, very fast breathing, blue, pale or blotchy skin, or not passing urine.
- Your temperature: a very high temperature, feeling hot, cold or shivery, or a temperature below 36°C.
- The pain: whether it is in the lower back or side, just under the ribs, on one side or both, and whether it spreads to the groin.
- Other symptoms: burning when you pee, peeing more often, blood in your urine, feeling or being sick, and whether you can keep fluids down.
- Pregnancy: whether you are pregnant or could be.
- Your health: kidney stones or other kidney problems, diabetes, a weakened immune system, earlier urine infections and results, and the medicines you take.
If the doctor thinks you could have a kidney infection, you are told where to go and how quickly. Do not drive yourself if you feel very unwell, and take a list of your medicines with you.
What are the symptoms of a kidney infection?
The typical signs are a high temperature and pain in the lower back or side, often with the symptoms of cystitis. Symptoms often begin suddenly, within a few hours. They include:
- a high temperature, chills or shivering
- pain in your lower back or side, just under the ribs, and sometimes in the groin
- feeling or being sick, and sometimes diarrhoea
- aching muscles and flu-like symptoms
- pain, burning or stinging when you pee, and needing to pee more often and urgently
- dark, cloudy, bloody or foul-smelling urine
What does kidney infection pain feel like?
An ache or pain in the lower back or side, under the ribs, usually on one side, because a kidney infection usually affects one kidney rather than both. It comes with feeling unwell and a temperature, which is what separates it from a sore back.
Symptoms in older people
Older people may become confused rather than having the typical symptoms, and they may take longer to recover. New confusion with a urine infection needs urgent assessment.
Cystitis or a kidney infection?
Cystitis stays in the bladder. A kidney infection adds signs that the whole body is fighting the infection:
Swipe sideways to compare →
| Cystitis (bladder infection) | Kidney infection | |
|---|---|---|
| Where the infection is | The bladder | One or both kidneys |
| Main symptoms | Burning when you pee, peeing often, pain low in the tummy | The same, plus a high temperature and pain in the back or side |
| Treatment | Self-care and painkillers, a short course of antibiotics, or waiting 48 hours to see if it clears | A urine culture, then antibiotics for 7 to 14 days, sometimes in hospital |
| Online care | Usually treated online | Assessed online, treated in person |
More on bladder infections is on the cystitis and UTI pages.
What causes a kidney infection, and who is at risk?
Most kidney infections start as a bladder infection: bacteria, most often from the gut, get into the urinary system and travel up to the kidneys. Less often, bacteria reach a kidney through the blood. A kidney stone can block the flow of urine and let bacteria build up. These make a kidney infection more likely:
- being a woman: women get urine and kidney infections more often, though anyone can get one
- kidney stones or other kidney problems
- diabetes that is less well controlled, or a weakened immune system
- pregnancy
- being over 65
- being in hospital
Kidney infections are less common in men, so a man with a kidney infection usually needs tests to look for a cause. Having more than one kidney infection is also a reason for tests.
How serious is a kidney infection?
Most kidney infections get better with antibiotics, and people usually make a full recovery. Early treatment prevents most complications. Left untreated, a kidney infection can lead to:
- Sepsis: a serious reaction to an infection that can be life-threatening. It is uncommon after a kidney infection, but it usually develops quickly, over a few hours, which is why the warning signs mean 112.
- An abscess: a pocket of pus in or around the kidney.
- Kidney damage: repeated or ongoing infections can damage the kidneys.
The signs of sepsis
Call 112 for someone with a urine or kidney infection who:
- is confused, has slurred speech or is not making sense
- is breathing very fast
- has blue, pale or blotchy skin
- has a very high or very low temperature, or feels hot or cold to the touch and shivery
- has a rash that does not fade when you press it
- has stopped passing urine
What could be mistaken for a kidney infection?
Several conditions cause pain in the back, side or lower tummy with a temperature or urinary symptoms. These clues help, but only an examination and tests can confirm the cause:
Swipe sideways to compare →
| Condition | Where the pain is | Other clues | What to do |
|---|---|---|---|
| Kidney infection | Lower back or side, under the ribs, usually one side | High temperature, feeling sick, burning when peeing | Urgent in-person care; call 112 for signs of sepsis |
| Kidney stones | Starts in the side or lower back and can spread to the groin; comes and goes in waves | Severe pain, cloudy pee, feeling sick; a temperature with stones needs urgent help | Urgent help for severe pain or a temperature |
| Pelvic inflammatory disease | Low in the pelvis, deep inside during sex | Unusual discharge, bleeding between periods or after sex | Prompt examination; call 112 for severe pain |
| Cystitis | Low in the tummy | Burning and frequent peeing, no high temperature | Usually treated online |
Pain elsewhere in the tummy is covered in the stomach pain guide, and blood in the urine on its own on the blood in urine page.
What might the doctor recommend for symptoms that could be a kidney infection?
What happens next depends on how unwell you are, whether you are pregnant and how the infection is responding. This is the framework the doctors use, in line with NICE guidance:
Swipe sideways to compare →
| What you have | Likely first step | Suitable for online care? | When in-person care is needed |
|---|---|---|---|
| Confusion, drowsiness, very fast breathing, blotchy skin or not passing urine | Emergency treatment | No | Call 112 now |
| A high temperature with pain in the back or side | A urine culture, an examination and antibiotics | No | Urgently, in person |
| Pregnant, with urinary symptoms and a temperature or back pain | Urgent assessment; hospital treatment may be needed | No | Urgently, in person |
| Burning and frequent peeing without a temperature or back pain | Assessment and treatment for cystitis | Yes | If a temperature or back pain develops |
| On antibiotics for a kidney infection, not improving after 48 hours | A review, with the urine culture result | Yes, to assess | If you get worse at any time |
| Recovering after a kidney infection | Advice on fluids, pain relief and returning to work | Yes | If the symptoms come back |
| More than one kidney infection, or a kidney infection in a man | Tests to look for a cause | Partly | For scans and tests |
Not sure whether your symptoms mean a kidney infection? A doctor can tell you in one consultation how urgently you need to be seen.
See available times →How is a kidney infection treated?
With antibiotics, after a urine sample has been sent for culture. Most people take antibiotic tablets for 7 to 14 days. The culture result can take several days, so treatment usually starts before it is back, and the antibiotic is changed if the bacteria turn out to be resistant. If you are not improving within 48 hours of starting antibiotics, or you get worse, you need a review.
Some people need antibiotics through a drip in hospital, which works faster than tablets: for example when the infection is severe, in pregnancy, with a long-term condition, or when vomiting stops you keeping tablets down. Most people go home after 3 to 7 days.
What you can do yourself
- Rest, and drink plenty of fluids, in small sips if you feel sick. If you have kidney problems, ask your doctor how much to drink.
- Take paracetamol for pain and a high temperature.
- Do not take ibuprofen or other anti-inflammatory painkillers unless a doctor advises it, because they can harm the kidneys.
- Empty your bladder fully when you pee, and do not hold in urine when you need to go.
- Finish the antibiotics, even if you feel better.
Prescription treatment
A prescription is never issued without a consultation. A kidney infection is treated in person, after a urine sample has been sent for culture, with antibiotic tablets or, when you are very unwell, antibiotics through a drip in hospital, and no medicine at home replaces that. After treatment, the doctor may advise on pain relief and on what to do if the symptoms come back. Codeine and other opioid painkillers are never prescribed online. If the doctor prescribes, use the prescription at a pharmacy near you.
What does not help
Waiting at home with a high temperature and back pain to see whether it settles. Treating it as cystitis with leftover antibiotics, which can be the wrong medicine and course length. Diet changes, which do not treat a kidney infection. Ibuprofen, unless a doctor advises it.
How long does a kidney infection last?
Most people start to feel better around 2 weeks after starting treatment and make a full recovery. It can take up to 2 weeks before you feel able to go back to work, and older people and those with other health conditions may take longer.
Special situations
Pregnancy
Urinary symptoms with a temperature, or pain in the back or side, in pregnancy need urgent in-person care: a kidney infection in pregnancy may need treatment in hospital, and the antibiotic is chosen to be safe for the baby. Other urinary problems in pregnancy are covered on the bladder problems in pregnancy page.
Older people
A kidney infection can show up as confusion rather than the typical symptoms, and recovery can take longer. New confusion with a urine infection needs urgent assessment.
Men, diabetes and kidney problems
Kidney infections are less common in men, so a man with one usually needs tests to look for a cause, such as a kidney stone. Diabetes that is less well controlled, a weakened immune system and existing kidney problems make a kidney infection more likely and more serious, so they lower the threshold for in-person care.
A kidney infection while travelling in Europe
The warning signs mean 112 wherever you are. Otherwise, a high temperature with back pain needs a doctor in person, who can send your urine for culture. Keep the result and the name of the antibiotic, and take your discharge letter home: they matter if the infection comes back. Drink plenty of fluids, and take your usual medicines with you.
Children
Mobi Doctor consultations are for adults aged 18 and over. A child who is unwell needs a paediatrician or a local doctor in person, and emergency signs in a child mean 112.
When a kidney infection is assessed online, and when you need in-person care
Assessed online: urinary symptoms where it is unclear whether the kidneys are involved, how urgently you need to be seen, other likely causes, recovery after treatment, slow improvement on antibiotics, and repeated infections that need a plan.
In-person care: any suspected kidney infection, the urine culture, the examination and the antibiotics, kidney infection in pregnancy, scans and tests after repeated infections, and every emergency sign.
When to get in-person care
Call 112 or go to an emergency department now for:
- confusion, drowsiness, slurred speech or not making sense
- very fast breathing
- blue, pale or blotchy skin
- a rash that does not fade when you press it
- no longer passing urine
- a very high or very low temperature with feeling very unwell
Get medical advice the same day for:
- a high temperature, or feeling hot, cold or shivery, with urinary symptoms
- a temperature below 36°C with urinary symptoms
- pain in your back or side, just under the ribs, with urinary symptoms
- being sick, or unable to keep fluids down, with a urine infection
- urinary symptoms with a temperature in pregnancy
- no improvement 48 hours after starting antibiotics for a kidney infection
How Mobi Doctor works
- Book a time that suits you: daily 7am–11pm CET. You can see a doctor over video, usually within 15 minutes. No subscription, and the exact price is shown before you pay.
- Speak to a licensed doctor about your symptoms: give your temperature if you have taken it, say where the pain is, and mention pregnancy, diabetes, kidney problems and any recent antibiotics.
- Leave with a plan: what to do, what to take and for how long, and which signs mean you should be seen in person. If the doctor prescribes, use the prescription at a pharmacy near you.
No sign-up needed
Not sure it’s a kidney infection? Tick every symptom you have to see each condition page that mentions it. It finds the right page, not a diagnosis: a doctor gives you that on a video call. If you have an emergency sign listed on this page, call 112 instead.
Tap the body — an area or a point — to browse symptoms anywhere
Similar symptoms, different condition? UTI can start the same way. Compare them, or look up any other symptom in the full symptom checker.
Frequently asked questions about kidney infections
What are the symptoms of a kidney infection?
A kidney infection causes a high temperature, pain in the lower back or side under the ribs, feeling or being sick, and aching muscles, often with burning when you pee and needing to pee more often. Older people may become confused instead.
What does kidney infection pain feel like?
Kidney infection pain is an ache or pain in the lower back or side, under the ribs, usually on one side. It comes with a temperature and feeling unwell, which is what separates it from a sore back.
How serious is a kidney infection?
Most people recover fully with antibiotics. Untreated, a kidney infection can lead to sepsis, which can be life-threatening and usually develops quickly, over a few hours, so the warning signs mean calling 112.
When should I go to hospital with a kidney infection?
Go to hospital with a kidney infection if you are being sick and cannot keep antibiotics down, have a very high temperature with shivering and shaking, feel confused or unusually drowsy, are breathing very fast, have mottled, pale or blue skin, or have stopped passing urine, because these can mean sepsis; call 112 for the last four. Pregnancy, diabetes, a weak immune system or a kidney infection that is no better after 48 hours of antibiotics also need in-person assessment.
What causes a kidney infection?
Usually bacteria from the gut that cause a bladder infection and then travel up to the kidneys. Kidney stones, diabetes, a weakened immune system, pregnancy and older age make it more likely.
Can a kidney infection go away on its own?
It should not be left to settle. A kidney infection needs antibiotics after a urine sample has been sent for culture, because untreated it can lead to sepsis or kidney damage.
How can I prevent a kidney infection?
Most kidney infections start as bladder infections, so prevent those: drink enough to keep urine pale, do not hold urine in, pee after sex, wipe front to back, avoid spermicide, treat cystitis promptly and finish the antibiotics, keep diabetes controlled, have kidney stones or an enlarged prostate treated, and after the menopause ask about vaginal oestrogen if infections recur. Pregnant women are screened for bacteria in the urine because a kidney infection in pregnancy is more dangerous.
What antibiotics treat a kidney infection?
A kidney infection is treated with antibiotic tablets, usually for 7 to 14 days, chosen around pregnancy, allergies and the urine culture result, or antibiotics through a drip in hospital if you are very unwell. The doctor treating you in person makes the choice.
How long does a kidney infection last?
Most people with a kidney infection start to feel better around 2 weeks after starting treatment. It can take up to 2 weeks before you feel ready for work, and longer for older people or those with other conditions.
What could be mistaken for a kidney infection?
Kidney stones, pelvic inflammatory disease, cystitis and back problems can feel similar. A temperature with pain in the back or side and urinary symptoms points to the kidneys, and only an examination and tests confirm it.
What is the best way to flush out a kidney infection at home?
You cannot flush it out: it needs antibiotics. Drinking plenty helps, in small sips if you feel sick, unless a doctor has told you to limit fluids because of kidney problems.
Is a kidney infection the same as a UTI?
A kidney infection is a type of urinary tract infection, usually one that started in the bladder and spread to the kidneys. It is more serious than cystitis and is treated in person.
Can an online doctor treat a kidney infection?
No. A doctor by video can judge whether your symptoms could be a kidney infection and how urgently you need to be seen, but the urine culture, the examination and the antibiotics are in person.
- Kidney infection, NHS, National Health Service (UK), reviewed 13 February 2025.
- Pyelonephritis (acute): antimicrobial prescribing (NG111), NICE, National Institute for Health and Care Excellence, October 2018.
- Kidney infections, Kidney Research UK, reviewed April 2026.
- Kidney infection (pyelonephritis), NIDDK, US National Institute of Diabetes and Digestive and Kidney Diseases, reviewed October 2024.
- Symptoms and causes of kidney infection, NIDDK, US National Institute of Diabetes and Digestive and Kidney Diseases, reviewed October 2024.
- Sepsis, NHS, National Health Service (UK), reviewed 14 May 2026.
- Urinary tract infections (UTIs), NHS, National Health Service (UK), reviewed 11 July 2025.
- Kidney stones, NHS, National Health Service (UK), reviewed 17 September 2026.
- Pelvic inflammatory disease (PID), NHS, National Health Service (UK), reviewed 17 December 2025.
This page is for information only and is not a substitute for a medical consultation. Guideline links are provided for transparency; treatment decisions are made with your doctor.
Related conditions
Related reading from the Mobi Doctor blog
Speak to a doctor about a possible kidney infection over video, usually within 15 minutes
Licensed doctors · open daily 7am–11pm CET · exact price before payment
See available times →