Kidney Stones: Symptoms, Treatment, and Preventing the Next One

People who have passed a kidney stone tend to describe it in terms usually reserved for major trauma. The pain is severe, it arrives without warning, and it comes in waves that build to something almost unbearable and then subside, only to return.

What makes stones worth understanding properly is that they recur. A substantial proportion of people who have one stone will have another within a decade. That makes prevention genuinely worthwhile, and prevention depends on knowing what kind of stone you had, which is information many people never obtain.

This guide covers why stones form, what an episode involves, how they are treated, and what actually reduces the chance of a repeat.

How Kidney Stones Form

Urine carries dissolved minerals and salts. When the concentration of certain substances rises, or when the substances that normally keep them dissolved are lacking, crystals begin to form. Those crystals aggregate over time into stones.

The process depends on three broad factors: how concentrated the urine is, the chemical composition of the urine including its acidity, and the presence or absence of natural inhibitors that prevent crystallisation. This is why low fluid intake is such a consistent risk factor. Concentrated urine makes crystallisation easier regardless of everything else.

The Main Stone Types

Calcium stones account for the large majority. Most are calcium oxalate, with a smaller proportion calcium phosphate. Contributing factors include low urine volume, high urinary calcium or oxalate, and low urinary citrate, which is a natural inhibitor.

 

Uric acid stones form in persistently acidic urine and are associated with gout, metabolic syndrome, type 2 diabetes, high animal protein intake, and chronic diarrhoea. Our guide to gout and uric acid management covers the related metabolic picture.

Struvite stones form in the presence of certain urinary tract infections. They can grow large and fill the collecting system, and they require both stone removal and infection treatment.

Cystine stones result from an inherited disorder of amino acid transport. They are uncommon, often begin in childhood or early adulthood, and tend to recur persistently, requiring specialist management.

Knowing which type you had changes the prevention plan entirely, which is why straining urine to catch a passed stone for analysis is genuinely worth the inconvenience.

Risk Factors

• Inadequate fluid intake, the single most modifiable factor
• Previous stones or a family history
• Hot climates and heavy sweating, including occupational heat exposure
• Excess body weight, insulin resistance, and metabolic syndrome
• High sodium intake, which increases urinary calcium
• High animal protein intake, which raises acid load and urinary calcium and lowers citrate
• Very high oxalate intake in susceptible individuals
• Certain gastrointestinal conditions such as inflammatory bowel disease, chronic diarrhoea, and previous bariatric surgery, which increase oxalate absorption
• Some medications and supplements, including certain diuretics and high-dose vitamin C
• Hyperparathyroidism and other metabolic conditions
• Recurrent urinary tract infections, for struvite stones specifically

What an Episode Feels Like

A stone sitting in the kidney often causes nothing at all. Symptoms begin when it moves into the ureter, the narrow tube draining to the bladder, and obstructs urine flow. Pressure builds behind the blockage, and that is what hurts.

Typical features include:

• Severe pain in the flank or side, often radiating toward the groin
• Pain in waves rather than constant, reflecting ureteric spasm
• Inability to find a comfortable position, with people often pacing or restless
• Nausea and vomiting
• Blood in the urine, sometimes visible and often only detectable on testing
• Urinary urgency and frequency as the stone nears the bladder
• Pain that shifts location as the stone descends

When It Is an Emergency

Seek urgent medical care for any of the following:

• Fever or chills with stone pain. This suggests infection behind an obstruction, which can progress to sepsis rapidly and requires urgent drainage.
• Inability to pass any urine
• Uncontrolled vomiting preventing fluid intake
• Pain not controlled by prescribed medication
• A single functioning kidney or a transplanted kidney with stone symptoms

The fever point deserves emphasis. An obstructed, infected kidney is one of the genuine urological emergencies, and delay carries serious consequences.

Diagnosis

CT without contrast is the most sensitive test and is standard in emergency settings. It shows stone size, location, and any obstruction, and low-dose protocols reduce radiation exposure.

Ultrasound avoids radiation entirely and is preferred in pregnancy, in children, and for follow-up monitoring. It detects obstruction well but is less reliable for small stones in the ureter.

Plain x-ray shows some stone types but misses uric acid stones, which are not visible on x-ray.

Blood and urine tests assess kidney function, infection, calcium, and uric acid.

Our comparison of MRI, CT and ultrasound explains why each is chosen in different situations.

Treatment

Conservative Management

Most stones below a certain size pass without intervention. Management involves pain control, adequate fluid intake, and time. Some patients are prescribed a medication that relaxes the ureter to assist passage, though its benefit varies by stone size and location.

Passage typically takes days to several weeks. Straining urine through a filter to catch the stone allows analysis, which directly informs prevention. Ask for a strainer before leaving hospital, because the stone is easily lost otherwise.

Patients are usually followed up with repeat imaging to confirm passage, since a stone can obstruct silently after the pain settles.

Procedures

Shock wave lithotripsy uses focused energy waves delivered from outside the body to fragment the stone into pieces small enough to pass. It is non-invasive and suits certain stone sizes, locations, and compositions. Fragments still have to pass, which can cause discomfort afterward.

Ureteroscopy involves passing a thin scope up through the bladder into the ureter to visualise the stone directly, then fragmenting it with a laser and removing the pieces. A temporary stent is often left in place afterward to keep the ureter open. Stents commonly cause urinary urgency, discomfort, and blood in the urine until removed, which surprises patients who were not warned.

Percutaneous nephrolithotomy accesses the kidney through a small incision in the back and is used for large or complex stones, including staghorn stones filling the collecting system.

Emergency drainage, either by stent or by a tube placed directly into the kidney, is used when an obstructed kidney is infected. Definitive stone treatment follows once the infection is controlled.

Preventing Recurrence

This is where the long-term value lies, and it is frequently neglected because the acute episode dominates attention.

Fluid Intake

Increasing urine volume is the most consistently effective preventive measure across all stone types. The practical target is producing a substantial volume of dilute, pale urine throughout the day, which usually means drinking steadily rather than in bursts and increasing intake in hot weather or with heavy exercise. Discuss a specific target with your doctor, particularly if you have heart or kidney conditions where fluid intake needs care. Our guide to hydration and how much is enough covers general principles.

Dietary Adjustments by Stone Type

For calcium oxalate stones, the counterintuitive but well-established advice is to maintain normal dietary calcium rather than restricting it. Dietary calcium binds oxalate in the gut so that less is absorbed; restricting it increases urinary oxalate and worsens stone risk. Calcium supplements taken separately from meals are a different matter and should be discussed with your doctor.

Reducing sodium lowers urinary calcium and is one of the more effective changes. Moderating animal protein reduces acid load and raises citrate. Very high oxalate foods, such as spinach, rhubarb, beetroot, nuts, and certain teas, may be moderated in people with documented high urinary oxalate, though blanket restriction is not usually necessary.

For uric acid stones, the priority is raising urine pH, often with citrate supplementation, alongside reducing animal protein and addressing metabolic factors.

For struvite stones, complete stone clearance and control of urinary infection are the priorities.

For cystine stones, high fluid intake, urine alkalinisation, and specialist medication are used.

Citrus fruit and lemon juice increase urinary citrate, a natural inhibitor, which is why lemon water is often suggested. It is a reasonable habit rather than a treatment on its own. Our guide to building balanced meals covers how to make these adjustments without an overly restrictive diet.

Metabolic Evaluation

People with recurrent stones, a single stone at a young age, a strong family history, unusual stone composition, or a single kidney generally warrant a fuller workup. This typically includes a twenty-four hour urine collection measuring volume, calcium, oxalate, citrate, uric acid, sodium, and pH, alongside blood tests.

The results allow targeted treatment rather than generic advice, and specific medications exist for particular abnormalities. If you have had two or more stones and have never had a twenty-four hour urine study, it is reasonable to ask about one.

Recovering at Home After an Episode

Most people are sent home to pass the stone themselves, which means the bulk of the experience happens without medical supervision. A few practical points make that period more manageable.

Take pain medication on a schedule rather than waiting. Ureteric pain arrives in waves, and staying ahead of it works far better than chasing it once a wave has built. Follow the specific instructions given, and do not exceed them.

Keep drinking, but do not force enormous volumes at once. Steady intake through the day is more useful than drinking large amounts in bursts, which can worsen pain by increasing pressure behind an obstruction. If vomiting prevents you keeping fluids down, that is a reason to seek help rather than persist.

Strain every void. Stones are small and easily missed, and once flushed away the chance to have it analysed is gone. Keep the strainer in the bathroom and use it every single time, including at night.

Expect blood in the urine. Visible or microscopic blood is normal during passage and for a period afterward. Heavy bleeding with clots is not.

Attend the follow-up scan. A stone can stop hurting because it has moved into a position where it obstructs without causing colic, and a silently obstructed kidney can lose function over weeks. Do not skip follow-up because you feel better.

Know what should prompt a return. Fever, uncontrolled vomiting, inability to urinate, or pain that your medication is not touching all mean going back rather than waiting it out.

Frequently Asked Questions

How long does a stone take to pass?

It varies with size and position. Small stones often pass within days to a couple of weeks. Larger stones lower in the ureter may take longer, and stones above a certain size are unlikely to pass without intervention. Your doctor will advise how long to wait based on imaging.

Should I avoid calcium to prevent stones?

No, and this is one of the most persistent misconceptions. Restricting dietary calcium increases oxalate absorption and generally raises stone risk. Maintain normal dietary calcium and discuss any supplements with your doctor.

Does beer help pass stones?

Any fluid increases urine output, but alcohol also promotes dehydration and raises uric acid, so it is a poor choice. Water is better, and there is no evidence that any particular drink dislodges stones.

Will I definitely get another stone?

Not necessarily, but recurrence is common enough that prevention is worthwhile. Fluid intake and targeted measures based on stone type and urine chemistry meaningfully reduce that risk.

Why does my stent hurt more than the stone did?

Stents commonly cause urgency, frequency, flank discomfort during urination, and blood in the urine. This is expected and resolves once the stent is removed. Report fever, severe pain, or inability to urinate rather than assuming it is normal stent discomfort.

The Bottom Line

Kidney stone pain comes from obstruction rather than from the stone itself, which is why it arrives in waves and why it can be so severe. Most small stones pass with fluids, pain control, and patience, and larger ones have several effective procedural options.

The part most often missed is what happens afterward. Catch the stone if you can and get it analysed, because the type determines the prevention plan. Increase fluid intake enough to keep urine pale throughout the day, reduce sodium, keep dietary calcium normal rather than restricting it, and ask about a twenty-four hour urine study if you have had more than one stone. And treat fever alongside stone pain as an emergency rather than something to sleep on, because an infected obstructed kidney does not wait.