Kidney stones and renal colic: what they are, symptoms, treatment, and prevention

Oct 15, 2026 · @GPNutraceuticals

Kidney stones are small clusters of mineral salts that form in the kidneys when urine is too concentrated. Those under 4-5 mm usually pass on their own, while larger ones require treatment, such as lithotripsy or endoscopy. The typical symptom is renal colic, intense pain in the side that radiates toward the groin. The most effective prevention is drinking plenty of fluids: producing at least 2 liters of urine a day reduces recurrence by more than half. They are a common condition: in Italy, about 3 in 20 men and 2 in 20 women are affected, most often between the ages of 30 and 60.

In this guide, learn about the causes, symptoms, and treatments, when to go to the emergency room, how to prevent further episodes, and what studies say about citrate and supplements.

Reading time: 11 minutes

Last updated: October 2026

Scientific review: GP Nutraceuticals Team

Main sources: EAU guidelines on urolithiasis, Italian National Institute of Health, Cochrane reviews on water and citrate, clinical studies on potassium citrate and phyllanthus

What are kidney stones?

The kidneys filter the blood and produce urine. Kidney stones form when certain substances in the urine become too concentrated, or when substances that normally inhibit crystallization, such as citrate, are lacking. Substances such as calcium, phosphate, and other salts then form crystals that can cluster into stones of varying sizes: from sand-like grains, known as gravel, to a few centimeters.

Kidney stones, or renal calculi (medically known as nephrolithiasis), are common: according to the Italian National Institute of Health, they affect about 3 in 20 men and 2 in 20 women, especially between the ages of 30 and 60, and are rare before age 20. Anyone who has had a stone has a high chance of developing more: in an Italian study, without preventive measures, more than one in four people had another stone within five years.

Types of stones

Stones are classified according to their composition:

• calcium stones, about 75% of all stones, mostly calcium oxalate, alone or with calcium phosphate;
• uric acid stones, promoted by acidic urine;
• struvite stones, linked to some urinary tract infections;
• cystine stones, rare and caused by an inherited condition.

Knowing the type of stone, through analysis of a passed or removed stone, helps choose the most suitable prevention.

Kidney stones: 5 key points

The guide’s five key points: kidney stones are common, tend to recur, and can be prevented mainly by drinking more.

• They affect about 3 in 20 men and 2 in 20 women; about three out of four stones are calcium stones.
• Renal colic causes severe side pain: fever, uncontrollable vomiting, or pain that does not go away requires a trip to the emergency department.
• Stones smaller than 4-5 mm usually pass on their own; larger ones can be treated with lithotripsy or endoscopy.
• Drinking enough to produce at least 2 liters of urine a day more than halves the risk of further episodes.
• For recurrent stones, a doctor may prescribe potassium citrate; supplements can complement these measures, but not replace them.

What you’ll find in this guide

This guide starts by explaining what kidney stones are, then covers causes, symptoms, and treatment, and ends with prevention, supplements, and frequently asked questions.

• Causes and risk factors.
• Most common symptoms and when to go to the emergency department.
• Diagnosis and treatment.
• Prevention: water, diet, and medication.
• What studies say about citrate and supplements.
• Frequently asked questions.

This guide is for informational and educational purposes only and is not a substitute for advice from a doctor or other qualified healthcare professional.

What causes kidney stones?

In most cases, kidney stones do not form for just one reason, but result from a combination of overly concentrated urine and habits or conditions that increase the levels of substances that crystallize. The main risk factors are:

• drinking too little, especially in hot weather or when sweating a lot;
• a diet high in salt, animal protein, and sugar, and low in fiber;
• overweight and obesity;
• family history and previous kidney stones;
• certain intestinal diseases or surgeries, hyperparathyroidism, and inherited diseases such as cystinuria;
• certain medications, which a doctor can assess on a case-by-case basis.

A common mistake is to reduce calcium in your diet: with less calcium, the intestine absorbs more oxalate, which passes into the urine and can contribute to stone formation.

What are the symptoms of kidney stones and renal colic?

Stones can remain in the kidney, in the renal calyces, for a long time without causing problems: they often cause no symptoms and are found by chance during an ultrasound. Symptoms begin when a stone moves and blocks the ureter, the narrow tube leading to the bladder: this causes renal colic, along with other associated symptoms:

• sudden, very intense pain in your side or lower back, often described as “a stabbing pain,” that radiates toward your abdomen and groin;
• restlessness: you cannot find a position that brings relief;
• nausea and vomiting;
• frequent urination, burning when urinating, or blood in the urine.

When should you see a doctor about kidney stones?

It is worth discussing it with a doctor, without urgency, after a first kidney stone, if the colic recurs, or if an ultrasound finds stones by chance: tests can help identify the cause and plan prevention. However, go to the emergency department immediately if you have:

• fever of 38 °C or higher with chills, or cloudy, foul-smelling urine, which may be signs of an infection;
• pain that does not improve an hour after taking painkillers;
• vomiting that makes it impossible to drink;
• difficulty or inability to urinate;
• pregnant women, people with only one kidney, or people with known kidney disease.

A stone blocking an infected kidney is an emergency: in these cases, the kidney must be drained immediately before dealing with the stone.

How are kidney stones treated?

How are kidney stones diagnosed?

Kidney stones are confirmed through a physical examination, a urine test to check for blood and signs of infection, and blood tests to assess kidney function. Imaging tests include ultrasound, often the first choice because it is simple and uses no radiation, and CT without contrast, the most accurate test for detecting stones and measuring their size and location. Treatment depends on these factors and the symptoms: you may wait for the stone to pass on its own or have the stones removed.

Passing stones naturally and medication

Very small stones, about 4 mm or less, usually pass on their own, while stones measuring 6-7 mm or more generally need treatment. Pain is usually managed with anti-inflammatory drugs. For stones in the lower part of the ureter, your doctor may prescribe medication that relaxes the ureter and helps the stone pass. While waiting, it’s a good idea to urinate through a filter or strainer to catch the stone and have it analyzed.

Lithotripsy, ureteroscopy, and percutaneous nephrolithotomy

• Extracorporeal shock wave lithotripsy (ESWL): shock waves applied from outside the body break up the stone; it is often the first choice for stones that do not pass on their own, sometimes requiring multiple sessions.
• Ureteroscopy: a thin instrument is passed up the urinary tract to the stone, where it breaks it up with a laser under anesthesia.
• Percutaneous nephrolithotomy: used for large stones, which are removed through a small incision in the side.

Traditional surgery is now used in less than 1% of cases. After a kidney stone, especially a second one, your doctor may order blood tests and a 24-hour urine test to find out why it formed and plan prevention.

Preventing kidney stones: what to drink and eat?

Prevention matters because kidney stones tend to come back. The basic measures, which help prevent almost all types of kidney stones, are simple and accessible to everyone.

Drink more

It is the measure with the strongest evidence for reducing risk. In an Italian study of people experiencing their first kidney stone, those who drank enough to produce at least 2 liters of urine a day had another stone in 12% of cases over five years, compared with 27% of those who had not changed their habits. European guidelines recommend drinking 2.5-3 liters a day, spread throughout the day. Water is the best choice; it’s best to limit sugary drinks.

Diet

• A normal amount of calcium, about 1,000-1,200 mg a day from milk, yogurt, and cheese: in an Italian study of men with recurrent stones, a diet with normal calcium and less salt and animal protein almost halved recurrences compared with a low-calcium diet.
• Little salt, no more than 4-5 grams a day, because sodium leads to excess calcium in the urine.
• Moderate animal protein (meat, fish, cured meats), which makes urine more acidic.
• Fruit and vegetables every day, which provide potassium and citrate.
• Healthy weight and regular physical activity.

For calcium oxalate stones, a doctor may recommend limiting vegetables rich in oxalates, such as spinach, chard, and rhubarb, without eliminating calcium.

When medication is needed

For people with recurrent stones, a doctor may prescribe medications based on test results: for example, potassium citrate when urinary citrate is low, thiazide diuretics when urinary calcium is high, or allopurinol when uric acid is high.

Supplements and citrates for kidney stones: what do the studies say?

Citrate is the most studied substance: it binds to calcium, inhibits the formation of calcium crystals, and reduces urine acidity. In studies, it was used mainly as a medication, at doses determined by a doctor; evidence on plants is more limited.

Scientific evidence and regulatory claims are two different things. A claim permitted on a label describes a physiological function recognized by an authority and does not prove that a product prevents stones. Likewise, a favorable study alone does not authorize a claim.

Studies on citrates and plants

How much citrate is needed?

In studies showing positive results, potassium citrate doses are 30-60 mEq per day, or about 3-6.5 g, and are determined by a doctor based on test results. Excess potassium can be dangerous for people with kidney disease or those taking medications that retain potassium, such as some diuretics, ACE inhibitors, and sartans. For this reason, therapeutic doses of citrate should be used under medical supervision.

What a supplement can claim

Regulation (EU) 432/2012 does not provide for claims about kidney stones or their prevention. For the nutrients in this section, general claims are authorized: potassium contributes to normal muscle function, normal functioning of the nervous system, and the maintenance of normal blood pressure; magnesium contributes to electrolyte balance. For some plants, such as birch, the Ministry of Health permits claims about urinary tract function and the drainage of body fluids.

Frequently asked questions about kidney stones

Quick answers to common questions: how much water to drink, whether to eliminate calcium, which foods to avoid, whether lemon helps, whether a stone can be dissolved, and what happens in the emergency room for renal colic.

How much water should you drink to prevent kidney stones?

European guidelines recommend drinking plenty of water: 2.5-3 liters a day, spread throughout the day, and more in hot weather or when exercising. Urine color is a good indicator: it should be pale.

Should people with kidney stones eliminate calcium?

No. Contrary to popular belief, a low-calcium diet increases the risk of kidney stones. It's better to consume a normal amount of calcium, reduce salt, and moderate animal protein.

What foods should you avoid with kidney stones?

Rather than eliminating individual foods, it's better to limit salt, excess animal protein, and sugary drinks. For some types of stones, a doctor may give specific advice, such as moderating spinach, chard, and rhubarb or, for uric acid stones, reducing meat, fish, and seafood.

Does lemon help with kidney stones?

Lemon juice contains citrate, but the amounts in a normal lemonade often aren't enough to significantly change urinary citrate levels. A lime-based supplement providing about 55 mEq of citrate per day reduced stone recurrence in one study, but it is not a substitute for treatment prescribed by a doctor.

What should you drink to dissolve a kidney stone?

No drink can dissolve calcium stones, which are the most common type: water helps small ones pass and reduces the risk of more forming, but does not dissolve them. Only uric acid stones can dissolve, with treatment that raises urine pH: a doctor may prescribe potassium citrate and monitor over time to see whether the stone shrinks. Juices, herbal teas and natural remedies have not been shown to dissolve them.

Do kidney stones come back?

Often, yes: having kidney stones once increases the risk of getting them again. In one Italian study, more than one in four people developed a new stone within five years without preventive measures, while drinking more than halved this risk.

What do they do in the emergency room for renal colic?

The pain is controlled first, usually with injected anti-inflammatory drugs. Urine and blood tests are then performed, along with an ultrasound or CT scan, to confirm the presence of stones and locate them. If the stone is small, you can wait for it to pass on its own; if there is a fever or the kidney is blocked, urgent drainage may be needed.

In summary

Kidney stones are common, tend to recur and cause renal colic, meaning intense pain in the side. Small stones usually pass on their own; larger ones are treated with lithotripsy or endoscopy. Fever, uncontrollable vomiting or pain that does not go away require emergency care.

Prevention is based mainly on water, little salt, normal calcium intake and moderate animal protein. For recurrent stones, potassium citrate recommended by a doctor reduces recurrence; evidence for plants is still limited.

The GP Nutraceuticals nutraceutical approach

A supplement does not treat kidney stones and does not replace water, a proper diet or medicines prescribed by a doctor. It can complement these measures.

CalcoSin® Ultra is a food supplement in sachets that combines potassium citrate and magnesium citrate with extracts of phyllanthus, birch, saxifrage, pellitory and restharrow. One sachet a day, dissolved in a glass of water, provides 600 mg of potassium, 100 mg of magnesium and about 1.6 g of citrates.

Among the approved claims for its ingredients:

• potassium contributes to normal muscle function, normal nervous system function and the maintenance of normal blood pressure;
• magnesium contributes to electrolyte balance;
• Phyllanthus supports urinary tract function; birch, saxifrage and pellitory support urinary tract function;
• stonebreaker, pellitory, and restharrow promote the drainage of body fluids.

The potassium in one sachet corresponds to about 15 mEq, less than the doses of potassium citrate used in studies: the results of those studies therefore cannot be attributed to the product, which does not replace citrate prescribed by a doctor. Anyone with kidney disease or taking medicines that retain potassium should consult a doctor before use.

Scientific sources and references

This guide is based on three types of sources: guidelines from scientific societies, institutional sources such as the Italian National Institute of Health, and scientific studies published in peer-reviewed journals, including systematic reviews and randomized clinical trials.

Guidelines and institutional sources

1. European Association of Urology. EAU Guidelines on Urolithiasis. uroweb.org
2. Italian National Institute of Health – ISSalute. Kidney stones. issalute.it
3. Commission Regulation (EU) No 432/2012 on establishing a list of permitted health claims made on foods. eur-lex.europa.eu

Water and diet

4. Borghi L, Meschi T, Amato F, et al. Urinary volume, water and recurrences in idiopathic calcium nephrolithiasis: a 5-year randomized prospective study. J Urol. 1996. PMID: 8583588
5. Bao Y, Tu X, Wei Q. Water for preventing urinary stones. Cochrane Database Syst Rev. 2020. PMID: 32045491
6. Borghi L, Schianchi T, Meschi T, et al. Comparison of two diets for the prevention of recurrent stones in idiopathic hypercalciuria. N Engl J Med. 2002. PMID: 11784873

Citrates and plants

7. Phillips R, Hanchanale VS, Myatt A, et al. Citrate salts for preventing and treating calcium containing kidney stones in adults. Cochrane Database Syst Rev. 2015. PMID: 26439475
8. Ettinger B, Pak CY, Citron JT, et al. Potassium-magnesium citrate is an effective prophylaxis against recurrent calcium oxalate nephrolithiasis. J Urol. 1997. PMID: 9366314
9. Dissayabutra T, Anegkamol W, Ratchanon S, et al. Lime-based supplement reduces calcium oxalate stone recurrence: a multicenter randomized controlled trial. PLoS One. 2025. PMID: 41348736
10. Nishiura JL, Campos AH, Boim MA, et al. Phyllanthus niruri normalizes elevated urinary calcium levels in calcium stone forming (CSF) patients. Urol Res. 2004. PMID: 15221244
11. Cai T, Tiscione D, Puglisi M, et al. Phyllanthus niruri and Chrysanthellum americanum in association with potassium and magnesium citrates are able to prevent symptomatic episode in patients affected by recurrent urinary stones: a prospective study. Arch Ital Urol Androl. 2021. PMID: 34286553

Update history

We update this guide when new guidelines or relevant studies are published.

Version 1.0 – October 2026

First published. Main sources: EAU guidelines on urinary stones, the Italian National Institute of Health, Cochrane reviews on water and citrates, and clinical studies on potassium citrate, lime, and phyllanthus.