Symptoms · · 7 min read

Kidney stones: symptoms, treatment and prevention

Kidney stones are hard lumps that form in the kidneys when certain minerals build up in your urine. A small one may pass without you noticing; a larger one can cause some of the worst pain people describe. Most stones are managed with fluids and pain relief, but pain with fever needs urgent care, and the habits you build after the first stone matter most for keeping the next one away.

Illustration of a kidney with three yellow stones inside, next to a glass of water and a lemon slice

In short

  • A typical attack is severe pain in the side or back that comes in waves, may travel toward the groin, and often comes with blood in the urine.
  • Pain together with a high temperature or shaking chills is an emergency, not something to sit out at home.
  • Drinking enough water, mostly plain water, is the single most important step to keep stones from coming back.
  • Cutting calcium from your food is usually the wrong move; calcium eaten with meals can actually help block stone-forming substances.
  • Catching a passed stone and having it analyzed shows which type you have, so your prevention plan can be specific.

What kidney stones are

A kidney stone is a solid, pebble-like piece of material that forms in one or both kidneys when your urine contains high levels of certain minerals. Stones range from the size of a grain of sand to the size of a pearl. Many pass on their own through the urinary tract, and when a health care professional treats them they rarely cause permanent damage.

The trouble starts when a stone moves into the urinary tract and causes pain on its way out. Small stones that slip through easily may be noticed only in your urine, or not at all.

What an attack feels like

  • Sharp pain in the back, the side, the lower abdomen or the groin, often severe and coming and going.
  • Blood in the urine.
  • Nausea or vomiting.
  • A frequent urge to urinate, burning, or cloudy or foul-smelling urine.
  • Fever, feeling hot, or shivering, which points to a possible infection.

Small stones that move easily through the urinary tract may cause no symptoms at all, and you may only discover one when it shows up in your urine.

Why stones form and who gets them again

Stones form when chemicals in urine build up into hard lumps. The most common everyday reason is not drinking enough fluid. Medical conditions that raise certain chemicals in the body, such as metabolic syndrome, some inherited conditions and some medicines can also play a part.

  • A high-protein, low-fiber diet and too much sodium.
  • Being inactive or carrying extra weight.
  • Frequent kidney or urinary infections.
  • A close relative who has had stones, or having had a stone yourself.

That last point is the reason prevention starts after the very first stone rather than waiting for a second.

What to do during an attack

  1. Check for red flags first.Fever, shaking chills, vomiting that will not stop, or being unable to pass urine mean emergency care now.
  2. Call your clinician the same day.Even if the pain is manageable, a stone that causes symptoms should be assessed, especially if the pain is severe.
  3. Ask about pain relief.Most stones are treated at home with fluids and medicines for pain and nausea. Which medicine is safe depends on your kidneys and stomach, so take it as prescribed by a doctor.
  4. Keep drinking.Staying well hydrated is part of the plan. Check the color of your urine: dark urine suggests you need more fluid.
  5. Save the stone.If you are asked to, strain your urine and keep what passes. A laboratory can tell what the stone is made of.
  6. Follow up.Pain easing does not prove the stone has left. Passing it can take a few weeks, and a check confirms nothing is still blocking the flow.

When to see a doctor

Contact your primary care provider or an urgent care service if you have symptoms that fit a stone: severe back or side pain that does not ease, blood in the urine, burning when you urinate, or cloudy, foul-smelling urine. The same goes for any new pain in the side if you have had stones before.

Red flags, call 911: severe pain with a fever or shaking chills, inability to pass urine, or vomiting you cannot control. A fever during a stone attack can mean infection, so it is never something to wait out until morning.

How doctors confirm a stone

A clinician will ask about your symptoms, medical history, medicines, diet and family history, and examine you. Often that is enough to suspect a stone, and the next steps confirm it.

  • Urine tests, which can show blood, signs of infection and clues about what formed the stone.
  • Blood tests, which can help find what is behind the stone.
  • Imaging: a CT scan is common for adults, while an ultrasound is used for children and during pregnancy. Abdominal ultrasound and X-ray based urography are other options.
  • Stone analysis, when you have saved a passed stone or when one is removed.

Some people are later offered extra urine and blood tests to look for the cause behind repeated stones. Your clinician interprets these, not a general article.

How stones are treated

Most stones are treated at home with plenty of fluids and medicines for pain, nausea and, in some cases, to help the stone pass. This can take a few weeks.

A larger stone, or one that does not pass, may need a procedure. Options include shock wave lithotripsy, where shock waves from outside the body break the stone into smaller pieces, and ureteroscopy, where a thin scope is passed up the urethra to remove or break up the stone. For some stones a surgeon goes in through a small cut in the back instead. Which one fits depends on the size and position of the stone and on your anatomy.

Preventing the next stone

  1. Water first.Drinking enough liquid, mainly water, is the most important prevention step. Many professionals suggest six to eight 8-ounce glasses a day unless you have kidney failure or your clinician tells you otherwise.
  2. Add citrus.Fresh lemon juice in your water is a common suggestion, while fizzy, caffeinated and alcoholic drinks are best limited.
  3. Go easy on salt.Sodium should stay below the amount in about one teaspoon of table salt a day for most adults.
  4. Moderate animal protein.Beef, poultry, pork, eggs, fish and dairy can be trimmed back, with beans, lentils and dried peas as swaps, while keeping total protein adequate.
  5. Watch oxalate if you have calcium oxalate stones.Nuts, peanuts, rhubarb, spinach and wheat bran are the foods usually named, and you do not need to drop calcium to do this.
  6. Keep weight in check.Excess weight raises risk, and for uric acid stones losing weight is especially important.

Myth: stones mean you should avoid calcium

It sounds logical: most stones contain calcium, so remove calcium. In practice, calcium in food does not cause these stones. In the gut it can bind oxalate and keep stone-forming substances from reaching the urine.

Aim to get enough calcium from food, ideally with meals. Plant-based sources such as fortified juices and cereals are low in oxalate. Ask your clinician before starting calcium supplements.

Questions and answers

Do I need to avoid dairy if I have kidney stones?

Usually not. Calcium from food helps keep oxalate out of your urine, so most people with calcium stones are told to keep calcium at a normal level and reduce sodium and animal protein instead. Your own stone type decides the details.

How long does it take to pass a kidney stone?

It varies with the size and position of the stone. Many stones pass within a few weeks with fluids and symptom relief, and larger ones may need a procedure.

Can pee color tell me if I am drinking enough?

It is a handy everyday check. Pale urine suggests good hydration, while dark urine is a sign to drink more, unless your clinician has limited your fluids.

Why does the stone type matter?

Calcium oxalate, calcium phosphate, uric acid and cystine stones each have their own dietary advice. Uric acid stones, for example, respond especially to weight loss and less animal protein, while cystine stones depend mostly on fluids.

Are kidney stones dangerous?

Most cause pain rather than lasting harm when treated. The real concern is infection alongside a stone, which is why fever with pain is treated as an emergency.

Sources

  1. NIDDK — Kidney Stones
  2. NIDDK — Eating, Diet, & Nutrition for Kidney Stones
  3. MedlinePlus — Kidney Stones
  4. NHS — Kidney stones

Sources checked on 29 October 2026.

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