Kidney stones

Also called Renal colic, Ureteric stones

Crystals forming in the kidney. The pain is famous, and the combination with a fever is what actually kills people.

What it is

Around 1 in 10 people will have a kidney stone at some point. They form when the urine becomes concentrated and minerals crystallise.

The pain of a stone moving down the ureter, renal colic, is severe, comes in waves, and is frequently described as the worst pain a person has experienced.

Most stones pass on their own. The situation that must not be missed is a stone plus infection: an obstructed, infected kidney is a urological emergency that becomes sepsis rapidly and needs drainage within hours, not antibiotics and a wait.

Recurrence is common, around half within ten years, and prevention is simple and almost never discussed.

Signs you might notice

Severe pain in the back or side, coming in waves, often radiating to the groin.

Restlessness. People with renal colic pace and cannot get comfortable, unlike peritonitis where people lie still.

Blood in the urine, sometimes visible and often not.

Nausea and vomiting.

Fever, shivering or feeling very unwell alongside the pain: that combination is the emergency.

Difficulty passing urine, or passing very little.

How it can affect day-to-day life

Dehydration is the main driver and the main preventable factor. People who work outdoors, in hot kitchens, or who simply do not drink enough are at higher risk.

Recurrence prevention is straightforward and rarely explained: enough fluid to produce around 2.5 litres of urine a day, reduced salt, and normal calcium intake. Cutting calcium, which people assume they should, actually increases stone risk.

Stone analysis, if you can catch the stone, guides prevention and is often not offered.

Supporting someone well

Drink enough that urine stays pale, all day, every day. This is the whole of prevention.

Reduce salt, which increases calcium in the urine.

Do not cut dietary calcium; it makes stones more likely, not less.

Catch the stone by straining urine, and ask for it to be analysed.

Take pain relief properly. Anti-inflammatories are more effective than opioids for renal colic in most cases.

Recognise the emergency: pain plus fever or feeling very unwell means go to hospital now.

Ask about a 24-hour urine collection and prevention advice after a second stone.

Where to get help

Urgent GP or 111 for renal colic. A and E for pain with fever, vomiting, or inability to pass urine.

The British Association of Urological Surgeons publish clear patient information.

A single kidney, or a transplant, with a stone is always urgent.