Kidney stones

Overview

Kidney stones are small, hard lumps that form inside the kidneys. They build up slowly when the urine holds more of certain substances, such as calcium, oxalate or uric acid, than it can keep dissolved. The most common type is made of calcium oxalate. Other types are made of uric acid (often linked with gout), struvite (linked with urine infections) or cystine (from a rare inherited condition).

Many stones cause no symptoms at all and are found by chance on a scan. Trouble usually starts when a stone moves into the ureter (the thin tube that carries urine from the kidney to the bladder) and blocks the flow of urine. This causes renal colic: sudden, severe pain in the side or back that can spread to the groin and comes in waves. Most small stones pass out in the urine by themselves, helped by pain relief and good fluid intake. Larger stones, or stones that cause infection or a blockage, may need a hospital procedure.

Kidney stones are common and can affect people of any age. Men get them about twice as often as women. Stones often come back, so finding out what type of stone you had and changing a few daily habits, especially drinking more water, is an important part of care.

Symptoms

• Sudden, severe pain in the side of the tummy or lower back, often coming in waves
• Pain that spreads to the groin, the testicles or the area around the vagina
• Blood in the urine, which may make it look pink, red or brown
• Feeling sick (nausea) or being sick (vomiting)
• Needing to pass urine more often, or pain when passing urine
• Cloudy or bad-smelling urine
• High temperature (fever), chills or shivering, which can mean an infection
• No symptoms at all, especially with small stones that stay in the kidney

Causes and risk factors

Causes

• Urine that is too concentrated because of not drinking enough fluid, so crystals can form and grow into stones
• Too much calcium, oxalate, uric acid or other stone-forming substances in the urine
• Repeated urine infections, which can lead to struvite stones
• Health conditions that change the chemistry of the urine, such as gout, an overactive parathyroid gland (hyperparathyroidism) or long-term bowel disease with diarrhoea
• Rare inherited conditions such as cystinuria, which causes cystine stones
• Some medicines, including certain water tablets (diuretics), antacids, antibiotics and medicines for HIV

What makes it more likely

• Not drinking enough fluid and passing only small amounts of urine
• Living in a hot, dry climate
• Having had a kidney stone before, or a close family member with stones
• Being male
• Being overweight, or having diabetes, high blood pressure, metabolic syndrome or gout
• A diet high in salt or animal protein (such as meat), or a lot of oxalate-rich foods such as spinach
• Taking high-dose vitamin C supplements
• Being inactive or bed-bound for long periods

Complications

A stone that blocks the ureter can make urine back up and swell the kidney (hydronephrosis). If urine is trapped behind a stone and becomes infected, pus can collect in the kidney (pyonephrosis). This can quickly lead to sepsis, a life-threatening reaction to infection, and needs emergency drainage of the kidney. Stones can also cause repeated urine infections, and a blockage left too long can scar the kidney. People who form stones again and again, or who have struvite, uric acid or cystine stones, are more likely to develop long-term kidney damage (chronic kidney disease). Stones often come back: about half of people have another stone within ten years.

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Diagnosis

A doctor can often suspect a stone from the type of pain. They will ask about past stones, family history, diet and medicines, and examine your tummy and back. A urine test looks for blood, crystals and infection. Blood tests check kidney function and levels of substances such as calcium and uric acid.

Imaging confirms the stone. An ultrasound scan is often the first test and is preferred in pregnancy and for children. A CT scan without contrast dye is the most accurate way to find a stone and see if it is causing a blockage. A plain X-ray may be used to check later that a stone has passed. You may be asked to strain your urine to catch the stone, because guidelines advise testing the stone after a first episode. People at high risk of more stones may need 24-hour urine tests.

Treatment

1. Control the pain: an anti-inflammatory painkiller (NSAID) is usually the first choice. If this is not suitable or not enough, other painkillers can be used. Anti-sickness medicine and fluids can help with vomiting.
2. Wait for small stones to pass: most small stones pass by themselves. Drink plenty of water and catch the stone in a strainer so it can be tested. Being pain-free does not always mean the stone has gone, so follow-up may be needed.
3. Help the stone pass: for some stones in the lower part of the ureter, a doctor may prescribe an alpha-blocker, a medicine that relaxes the ureter so the stone can pass more easily.
4. Treat infection and blockage urgently: if a blocked kidney is infected, doctors start antibiotics straight away and drain the kidney with a thin tube (a stent inside the ureter, or a nephrostomy tube through the back). The stone itself is treated after the infection has cleared.
5. Remove stones that will not pass: if pain cannot be controlled or the stone is unlikely to pass, surgery is usually offered soon, often within about two days. Options include shock wave lithotripsy (breaking the stone with sound waves from outside the body), ureteroscopy (a thin telescope passed up through the urethra to remove or laser the stone) and percutaneous nephrolithotomy (removing a large kidney stone through a small cut in the back).
6. Prevent new stones: drink enough water every day, eat a balanced diet with normal calcium, and cut down on salt and animal protein. People at high risk, or with certain stone types, may be given medicine based on their stone and urine tests.

Medicines in Pakistan

Medicines a doctor may use, by group. Read the role: some are only for special cases. Each link opens our page for that medicine, with every brand and its official DRAP price. Your doctor decides which medicine and dose are right for you.

Also used (not yet in our price list): tamsulosin (alpha-blocker), silodosin (alpha-blocker), potassium citrate (urine alkaliniser)

Self-care and prevention

Self-care

• Drink water steadily through the day; water is the best choice
• Take extra care to drink enough in hot weather, because a hot climate raises the risk of stones
• Keep eating normal amounts of calcium-rich foods such as milk and yoghurt unless your doctor says otherwise; cutting calcium does not prevent stones
• Cut down on salt and salty foods
• Do not eat too much meat and other animal protein
• Avoid high-dose vitamin C supplements and, if your doctor advises, limit oxalate-rich foods such as spinach
• Keep to a healthy weight and stay physically active
• While waiting for a stone to pass, take pain relief as your doctor advises and catch the stone in a strainer to take to your doctor

Prevention

• Drink plenty of fluid every day, mostly water, so that you pass plenty of urine
• Eat a balanced diet with normal calcium, less salt and moderate amounts of animal protein
• Keep to a healthy weight and stay active
• If you have had a stone, ask whether it can be tested, so that advice and any medicine can match your stone type
• Have repeated urine infections checked by a doctor, as they can lead to some types of stone

Common questions

Can a kidney stone pass on its own?

Yes, most do. Most small stones pass in the urine without a procedure, helped by pain relief and good fluid intake. Larger stones, or stones causing a blockage, infection or pain that cannot be controlled, may need to be removed in hospital.

How much water should I drink to prevent kidney stones?

European urology guidelines advise most stone formers to drink about two and a half to three litres of fluid a day, preferably water, so that the body passes plenty of urine. Take extra care in hot weather, which raises the risk of stones. If you have heart or kidney problems, ask your doctor how much is right for you.

Should I stop eating dairy foods if I have calcium stones?

No. Guidelines say calcium in food should not be cut down unless there is a strong reason, and a very low calcium diet is not advised. Cutting down on salt and animal protein is more helpful.

Will my kidney stones come back?

They often do. About half of people who have had a stone get another one within ten years. Drinking enough water, eating a balanced diet and, for some people, taking medicine matched to the stone type can lower this risk.

Are kidney stones dangerous?

They are very painful, but most pass without causing lasting harm. The main danger is a stone that blocks the kidney and becomes infected, which can lead to sepsis. Fever or shivering with stone pain needs emergency care.

Sources

1. NICE. Renal and ureteric stones: assessment and management - Timing of surgery (early versus delayed intervention): intervention evidence review (consultation draft) (consultation draft) (2018).
2. European Association of Urology (EAU). Guidelines - EAU Guidelines on Urolithiasis - Uroweb (2026).
3. European Association of Urology (EAU). Metabolic Evaluation and Recurrence Prevention - EAU Guidelines on Urolithiasis - Uroweb (2026).
4. NHS. Kidney stones - NHS (2026).
5. MedlinePlus (US National Library of Medicine). Kidney stones: MedlinePlus Medical Encyclopedia (2026).
6. StatPearls (NCBI Bookshelf). Renal Calculi, Nephrolithiasis (2024).
7. Journal of the Pakistan Medical Association (Buchholz NPN et al., Aga Khan University). The Prevalence of Silent Kidney Stones - an Ultrasonographic Screening Study (2003).

Prepared from the sources listed below by the MedInfoBase team. Last reviewed 16 October 2026. This page is general health information, not medical advice. It gives no doses and does not replace a doctor: talk to your doctor or pharmacist before starting, stopping or changing any medicine. How we write and check our pages.

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Urinary tract infection (UTI)Chronic kidney diseaseGoutType 2 diabetes mellitus

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