The short answer: back pain from a muscle usually sits low in the back, feels like a dull ache and gets worse when you bend, twist or lift. Kidney pain is usually felt deeper, higher up under the ribs on one side, doesn’t change much when you move, and often comes with fever, feeling sick or changes when you pee. If you have those extra symptoms, get checked the same day.
Cleveland Clinic says people often mistake back pain for kidney pain. Here’s how to tell them apart, and what to do about each.
How do I know if it’s kidney pain or back pain?
You can usually tell kidney pain from back pain by where it sits, whether movement changes it and whether you have other symptoms such as fever or pain when you pee. This table puts the clues side by side, from Cleveland Clinic, the NHS and MedlinePlus:
| Clue | Muscle back pain | Kidney pain |
|---|---|---|
| Location | Usually the lower back, often over or beside the spine | Your side (flank), under the ribs, on one or both sides of the spine |
| Feel | Usually a dull ache, sometimes spasms | Deeper; a constant dull ache, or severe sharp pain that comes in waves |
| Movement | Worse when you bend, twist, lift, laugh or sneeze, or press on the spot | Doesn’t usually get worse when you move |
| Where it spreads | Into the buttock or down the leg if a nerve is involved | Toward the groin and inner thigh |
| Fever | Not usually | Common with a kidney infection, possible with a stone |
| Urine changes | None | Pain or burning when you pee, peeing often, cloudy, dark or bloody pee |
| Feeling unwell | No, apart from the pain | Often feeling or being sick, chills, flu-like aches |
MedlinePlus puts it simply: if flank pain comes with fever, chills, blood in the urine, or a frequent or urgent need to pee, a kidney problem is the likely cause.
Where is kidney pain felt?
Kidney pain is felt under your ribs, on one or both sides of your spine, in the area called the flank. Cleveland Clinic explains that your kidneys sit behind your stomach and under your rib cage, and you usually feel kidney pain on one side. It can spread to your belly or groin. The NHS says kidney stone pain usually starts in the side of your tummy or lower back and may spread to the groin, the testicles or the area around the opening of the vagina.
Ordinary back pain sits lower and closer to the middle. Cleveland Clinic notes that hip pain can be confused with kidney pain too, but it sits lower still. If your pain is on the right and low down, our guide to lower right back pain covers the other causes, including appendicitis.
Does kidney pain hurt when you move?
Kidney pain doesn’t usually get worse when you move, according to Cleveland Clinic, and that’s one of the most useful clues. A strained back muscle often hurts more when you bend, twist, lift something heavy, laugh or sneeze. Cleveland Clinic adds that pain from muscles and bones often gets worse when you press on the sore spot.
Kidney stone pain has its own rhythm. The NHS says it may come and go, with very severe spells and calmer ones in between. If bending or twisting reliably sets your pain off, a muscle or joint is more likely.
What’s the difference between a kidney stone and a kidney infection?
A kidney stone usually causes sudden, severe pain that comes in waves, while a kidney infection usually makes you feel ill, with a high temperature and pain when you pee. Both can cause pain in your back or side, and a stone can lead to an infection.
| Kidney stone | Kidney infection | |
|---|---|---|
| What it is | A hard lump of minerals that forms in the kidney | A urinary tract infection that has reached one or both kidneys |
| Pain | Severe, sharp, comes and goes in waves; spreads to the groin | Pain in the lower back or side, just under the ribs |
| Other symptoms | Feeling sick, peeing often, cloudy or bloody pee; fever is possible | High temperature, shivers, feeling or being sick, burning when you pee, dark or cloudy pee, flu-like aches |
| How common | About 1 in 10 people get one in their lifetime | More common in women, but anyone can get one |
| Usual treatment | Most pass in the pee within a few weeks; larger ones may need a procedure | Antibiotics from a doctor; you usually feel better after about 2 weeks |
Sources: the NHS pages on kidney stones and kidney infection, Cleveland Clinic and NIDDK on kidney stones. Small stones often cause no symptoms at all, the NHS says, and pass without you noticing.
To lower your chance of stones, the NHS advises drinking enough that your pee stays pale, and says adults should aim for 2.5 to 3 litres of water a day to help prevent them. Our guide to how much water you should drink explains how to check if you’re getting enough.
What tests will a doctor do for kidney pain?
For kidney pain, a doctor usually starts with a urine test, and may add blood tests and a scan. Cleveland Clinic, the NHS, NIDDK and MedlinePlus describe these:
| Test | What it checks |
|---|---|
| Urinalysis | Blood, bacteria, white blood cells and minerals in your pee; white cells and bacteria suggest an infection |
| Urine culture | Which bacteria are causing an infection |
| Blood tests | How well your kidneys are working, signs of infection, and minerals that can form stones |
| CT scan | The size and position of a stone and whether it’s blocking the urinary tract |
| Ultrasound | Stones and swelling; the NHS uses it in pregnancy and for children |
| Spine X-ray or MRI | Injuries or changes in the spine, if the back looks like the source |
The doctor will also ask where it hurts, whether it comes and goes, and whether bending makes it worse. Before your visit, note when the pain started, any fever and any changes when you pee.
When is kidney pain an emergency?
Kidney pain is an emergency if the pain is severe and unmanageable, you can’t pee, you can’t keep fluids down, or you feel confused, drowsy or very unwell. The NHS warns that an untreated kidney infection can cause sepsis.
Call 911, your local emergency number, or go to the ER if you have:
- Confusion, drowsiness or trouble speaking
- Severe pain you can’t manage, or severe belly pain
- Not being able to pee, or not having peed all day
- Vomiting so often you can’t keep anything down
- Back pain with numbness in both legs, or loss of bladder or bowel control
Get a same-day appointment if you have back or side pain with: a high temperature or shivers, blood in your pee, pain when you pee, or feeling sick. Get seen quickly if you’re pregnant. These come from the NHS and Cleveland Clinic. Ask a doctor before taking ibuprofen if you think your kidneys are involved. The NHS and Cleveland Clinic both say it may raise the risk of further kidney problems.
How do you relieve back muscle pain?
To relieve back muscle pain, stay active, use a wrapped ice pack or heat pack, and do gentle exercises. The NHS says back pain often improves on its own within a few weeks. Its advice:
- Keep moving and carry on with your daily activities as best you can. Don’t stay in bed for long periods.
- Ice for pain and swelling, heat for stiffness and spasms. Wrap either in a tea towel.
- Do gentle stretches. These five exercises for lower back pain are a good start. Stop if the pain gets worse.
- Try walking, swimming, yoga or Pilates, which the NHS says may help ease back pain.
Keep the free back pain rescue card handy for flare-ups, and see how to get rid of back pain for what the guidance does and doesn’t recommend. See a doctor if it isn’t better after a few weeks or it’s worse at night.
Your next step
Run through the table now. If you have fever, pain when you pee or blood in your pee, call your doctor today. If it’s your back, stand up, walk for a few minutes and try one stretch. For a routine laid out day by day, The Back Pain Reset below sets out ten-minute sessions for 28 days.
If your back is holding you back
The Back Pain Reset
A simple 28-day plan with ten-minute sessions, 12 exercises with pictures and a rescue card. Only $3.
Quick questions
How can I tell if it’s kidney pain or back pain?
Check where it hurts, whether movement changes it and what else you feel. Back muscle pain usually sits lower and gets worse with bending or twisting. Kidney pain sits higher, under the ribs to one side, doesn’t usually change with movement, and often comes with fever, nausea or changes when you pee, according to Cleveland Clinic.
Where is kidney pain felt?
Kidney pain is felt in your side or back, under your ribs, on one or both sides of your spine. Cleveland Clinic says it’s usually on one side and can spread to your belly or groin. The NHS says kidney stone pain may spread to the groin, testicles or the area around the vagina.
Does kidney pain get worse when you move?
Kidney pain doesn’t usually get worse when you move, according to Cleveland Clinic. Pain from a strained back muscle often does, especially when you bend, twist, lift something heavy, laugh or sneeze. If bending or twisting reliably sets it off, a muscle or joint is the more likely source.
Can kidney pain come and go?
Yes. Kidney stone pain often comes and goes in waves, the NHS and Cleveland Clinic say, with very severe spells and calmer spells in between. A kidney infection usually causes a more constant pain with fever. Either one needs a same-day check if the pain is severe or comes with fever.
What does kidney pain feel like in women?
Kidney pain feels much the same in women and men: a deep ache or sharp, wave-like pain in the side or back under the ribs. The NHS says stone pain may spread to the area around the vagina. Kidney infections are more common in women, so watch for fever and burning when you pee.
What will the ER do for kidney pain?
In the ER, doctors usually check your urine for blood and infection, take blood tests, and may order a CT scan or ultrasound to look for a stone or blockage. The NHS says adults with severe stone pain may be sent for a CT scan. Treatment depends on what they find.
This article is general information, not medical advice. Back pain and kidney pain can overlap, and only a doctor can tell them apart for sure. Get same-day help for back or side pain with fever, pain when you pee or blood in your pee. If you take medicines, check with a pharmacist or doctor before adding a painkiller.
Sources
- Cleveland Clinic. Kidney Pain: Causes, Treatment and When To Call a Doctor
- Cleveland Clinic. Flank Pain: Causes, Symptoms, Diagnosis and Treatment
- Cleveland Clinic. Kidney Stones
- Cleveland Clinic. Kidney Infection (Pyelonephritis)
- NHS. Kidney stones
- NHS. Kidney infection
- NHS. Back pain
- MedlinePlus. Flank pain, 2025
- MedlinePlus. Kidney stones
- NIDDK. Symptoms and Causes of Kidney Stones
- NIDDK. Diagnosis of Kidney Stones