How do you get kidney stones?

You get kidney stones when chemicals in your pee build up and form crystals, which grow into hard lumps. Your kidneys filter unwanted chemicals out of your blood and into your urine. BAUS says a stone can form when:

• there’s too much of certain chemicals in your urine
• there’s too little of the chemicals that stop crystals forming
• there isn’t enough urine to stop the chemicals crystallising

That’s why not drinking enough matters so much. Kidney Care UK, the kidney patient charity, says the biggest factor in all stone formation is how concentrated your urine is. Stones can be as small as a grain of sand, or up to a few centimetres across.

Most kidney stones are calcium stones. BAUS gives these shares:

Gout is caused by too much uric acid in your blood. The NHS says that gout which isn’t treated over a long time can lead to kidney stones.

You’re more likely to get kidney stones if you don’t drink enough water. The NHS also lists:

• medical conditions: ones that raise the amount of certain chemicals in your body, such as metabolic syndrome
• certain medicines: including aspirin, antacids, diuretics and antibiotics

Kidney stones can come back. The NHS says you’re more likely to keep getting them if you:

• eat a high-protein, low-fibre diet
• are inactive or bed-bound
• often have kidney or urine infections
• have a close family member who gets kidney stones
• have had kidney stones before

BAUS adds that a diet high in animal protein, refined sugar and salt raises the risk, that men are affected slightly more often than women, and that the peak age for a first stone is around 45. If you think a medicine could be playing a part, talk to your doctor before you stop taking it.

Small kidney stones often cause no symptoms. Larger ones can cause severe pain. You may pass a small stone when you pee without noticing. The NHS says kidney stone pain:

• usually starts in the side of your tummy or your lower back
• may spread to your groin, your testicles or the area around the opening of your vagina
• may come and go, with times when it’s very severe and times when it eases or goes away

You may also have:

• a high temperature, or feel hot, cold or shivery
• feeling sick or being sick
• a need to pee often
• pee that looks cloudy

BAUS also lists blood in your urine and burning when you pee.

Get urgent medical help if you think you have a kidney stone and you’re in severe pain, or you have a high temperature or feel hot, cold or shivery. That’s the advice from the NHS.

A stone that blocks a kidney which is also infected is an emergency. Kidney Care UK says it needs treatment in hospital the same day, and that the signs are pain in your side with a fever. If you have both, get urgent medical help straight away.

Blood in your pee always needs checking urgently, even if there’s only a small amount. The NHS says it’s not usually anything serious, but it can be a sign of cancer.

Pain in your side, cloudy pee and needing to pee often aren’t always caused by kidney stones. Other causes include:

• a urinary tract infection (UTI): burning pain when you pee, needing to pee more often, cloudy pee and sometimes blood in your pee
• a kidney infection: pain in your lower back or side, with a high temperature and feeling or being sick
• an STI: the NHS lists pain when peeing as a symptom of an STI, and many STIs have no symptoms at all
• an enlarged prostate: in men over 50, finding it difficult to pee and needing to pee suddenly and often

Read more in “Is blood in urine a symptom of an STI?” and “Is a UTI an STI? How to tell the difference”

Most kidney stones can be treated at home with medicine, according to the NHS.

How kidney stones are diagnosed

A doctor can usually diagnose kidney stones from your symptoms. Sometimes you’ll need urine or blood tests. If you have severe pain, you may be sent to hospital for a scan. The National Institute for Health and Care Excellence (NICE) recommends a CT scan within 24 hours for adults, or an ultrasound scan if you’re pregnant or under 16.

How kidney stones are treated

• at home: you’ll be advised to drink lots of water, and you may be offered painkillers, anti-sickness medicine and medicine to help the stone come out. A stone may take a few weeks to pass
• shock waves: used from outside your body to break up the stone so it’s easier to pass. NICE recommends this first for stones under 10mm
• a thin tube or keyhole surgery: a long, thin tube is passed up your urethra, the tube you pee through, or through a small cut in your back. This is done under general anaesthetic for larger stones

Which procedure you’re offered depends on how big the stone is and where it is.

Drinking enough water comes first. The NHS advises:

• water: drink 2.5 to 3 litres a day if you’re an adult. If your pee is dark, you need to drink more
• lemon juice: add fresh lemon juice to your water
• other drinks: avoid drinking lots of fizzy, caffeinated or alcoholic drinks
• salt: keep to less than 6g a day
• calcium: make sure you’re getting enough in your diet

Cutting down on calcium doesn’t help. BAUS says you shouldn’t restrict it even if your stone was made of calcium, because a normal intake helps protect you from future stones.

NICE says up to half of people with kidney stones get them again within 5 years, so these habits are worth keeping. The NHS says not to change your diet without speaking to your doctor.

No blood test can show whether you have a kidney stone. Stones are diagnosed from your symptoms and, if needed, a scan. If you have symptoms now, get medical help first.

If you’ve had gout or a kidney stone and you’d like to know your levels, Better2Know offers:

• Uric Acid: a blood test at one of our clinics that measures the uric acid in your blood, with results within 2 days.
• Uric Acid Gout and Kidney Stones Nurse Kit: the same blood test, with a kit sent to your home and the sample taken by a nurse, with results in 2 days.
• Kidney Function: a blood test that measures 5 markers, including urea and creatinine, to show how well your kidneys are working, at a clinic or with a nurse visit, with results in 1 day.

A high uric acid level is the main risk factor for gout, but Lab Tests Online UK says most people with high uric acid never develop symptoms. A normal result doesn’t rule out a kidney stone either, because most stones are made of calcium. Not sure which test you need? Our Patient Care Team is available 24/7 on 020 7099 0955.

How long does a kidney stone take to pass?

The NHS says a stone may take a few weeks to pass. BAUS says stones larger than 6mm are less likely to pass by themselves, and that treatment is usually recommended if a stone shows no sign of passing after 2 to 3 weeks.

Can kidney stones damage your kidneys?

They can if they keep coming back or are left untreated. The NHS lists kidney stones that keep coming back among the causes of chronic kidney disease. It’s uncommon for them to cause kidney failure: in a study from Australia and New Zealand, stones were the cause for about 1 in 100 people starting dialysis or having a transplant.

Does gout cause kidney stones?

It can. Gout is caused by too much uric acid in your blood, and the NHS lists kidney stones among the problems that gout can lead to if it isn’t treated over a long time.

So, how do you get kidney stones? Chemicals in your pee build up and form crystals, most often when you’re not drinking enough. Most kidney stones can be treated at home, and drinking 2.5 to 3 litres of water a day lowers the chance of another one. If you think you have a kidney stone and you’re in severe pain or have a high temperature, get urgent medical help.

If you’ve had gout or a kidney stone and you’d like to check your uric acid level, book a Uric Acid test at a clinic near you. Our Patient Care Team is available 24/7 on 020 7099 0955.

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This article originally appeared on 11 August 2023 and was last updated on 3 October 2026.

This article is general information and not a substitute for personal medical advice.

Sources

1. NHS, Kidney stones, reviewed 17 September 2026. https://www.nhs.uk/conditions/kidney-stones/
2. NHS, Gout, reviewed 24 August 2023. https://www.nhs.uk/conditions/gout/
3. NHS, Chronic kidney disease, reviewed 22 March 2023. https://www.nhs.uk/conditions/kidney-disease/
4. NHS, Blood in urine, reviewed 25 September 2026. https://www.nhs.uk/conditions/blood-in-urine/
5. NHS, Kidney infection, reviewed 13 February 2025. https://www.nhs.uk/conditions/kidney-infection/
6. NHS, Urinary tract infections (UTIs), reviewed 11 July 2025. https://www.nhs.uk/conditions/urinary-tract-infections-utis/
7. NHS, Sexually transmitted infections (STIs), reviewed 13 May 2024. https://www.nhs.uk/conditions/sexually-transmitted-infections-stis/
8. National Institute for Health and Care Excellence, Renal and ureteric stones: assessment and management (NG118), recommendations, 2019. https://www.nice.org.uk/guidance/ng118/chapter/Recommendations
9. National Institute for Health and Care Excellence, Kidney stones: the care you should expect (NG118, information for the public). https://www.nice.org.uk/guidance/ng118/informationforpublic
10. British Association of Urological Surgeons, Kidney stones, March 2024. https://www.baus.org.uk/patients/conditions/6/kidney_stones
11. Kidney Care UK, Kidney stones. https://www.kidneycareuk.org/kidney-disease-information/kidney-conditions/kidney-stones/
12. Lab Tests Online UK, Uric Acid Test. https://labtestsonline.org.uk/tests/uric-acid-test
13. Cheikh Hassan H and others, Kidney failure from kidney stones: an ANZDATA study, Nephrology Dialysis Transplantation, 2025. https://academic.oup.com/ndt/article/40/2/320/7695325