"Silent" kidney stones produce no pain, but most stones cause pain so severe that it's unforgettable. Some even say that it's even more painful than childbirth. It may come in waves that begin in your lower back and move to your side or groin. Other symptoms of stones are nausea, fever, bloody urine, or burning on urination. You may also have risk factors, like a family history of stones, that make you more likely to have stones in the future.

What are kidney stones?

Within the kidney, miniature filters separate substances from your blood that your body doesn't need, which you excrete in urine. But under certain conditions, chemicals in the urine may form crystals. These crystals build up in the kidney and stick together to form a stone. Kidney stones may block the flow of urine through the urinary tract, causing severe pain.

How Kidney Stones Form

Fluid loss (dehydration) can make your urine so concentrated that stones form. Certain foods contain high amounts of the chemicals that sometimes crystallize into stones. Kidney infections foster stones by slowing urine flow or changing the acid balance of your urine.

The location, size, and shape of your stone usually determine your symptoms. Many stones cause sudden and severe pain, bloody urine, or infection. Others cause nausea or frequent, burning urination.

The size, shape and composition of your kidney stone help determine its cause and whether your stone is likely to pass by itself or if it will require more aggressive treatment.

Stone Size
Stone Shape
Stone Composition
A stone may be as small as a grain of sand or as large as a golf ball. Many small stones pass naturally. Medium-sized stones are often crushed with special "high-tech" equipment. Very large stones may need to be removed using an invasive procedure. Smooth, round stones may pass easily if they are small. Stones with sharp edges often lodge inside the kidney or ureter. Staghorn stones, which can fill the entire kidney, are too large to pass naturally.

Many stones are made up of more than one chemical. Most stones are made of calcium oxalate, a hard salt compound. Very hard stones sometimes don't respond well to Extracorporeal Shock Wave Lithotripsy (ESWL). Cystine and uric acid stones are also dense, but sometimes can be dissolved with medication. Infection stones are less dense.

Expectant Therapy
The vast majority of kidney stones are small enough -- about the size of a grape seed -- to pass naturally, a "wait and see" approach. It's very likely you'll be able to pass your stone naturally with expectant therapy.

Drinking lots of water: Water helps flush out stones by increasing urine production. Water also reduces your risk of new stones by diluting the chemicals in your urine. Drink 12 eight-ounce glasses of water a day and avoid liquids that dehydrate you, such as caffeine and alcohol.
Straining your Urine: To collect your stone for analysis by your doctor, strain all your urine. Use the strainer whenever you urinate, for as long as your doctor suggests. Be on the lookout for brown, gold, or black specks or tiny pebbles. These are kidney stones.
Follow-up: If you find a stone, bring it in to your doctor for analysis. The type of stone you have will determine the diet and prevention program your doctor recommends. You may need additional tests and x-rays in the future to ensure that new stones are not forming.
Prevention: Kidney stones can recur at any time, so your prevention program lasts a lifetime. Drink lots of water, follow your diet, take your medications, and have regular checkups.

Depending on what your stone is made of your doctor may be able to prescribe medication to dissolve them.

Stone Compositions
Calcium Oxalate Stone: Medication cannot dissolve calcium oxalate stones, but are often helpful in preventing them.
Uric Acid or Cystine Stone:
If you have a uric acid or cystine stone, your doctor may prescribe medications to dissolve your stone. You may take these medications for the rest of your life. Uric acid stones are caused by an overproduction of uric acid, which can be worsened by a high-meat diet. Cystine stones are uncommon and are inherited, a result of too much cystine (an amino acid) in your urine.
Infection Stone:
If you have an infection stone, your doctor may prescribe antibiotics. When your infection is under control, your doctor can remove your stone. Infections stones are caused by kidney or bladder infections that change the chemical balance of your urine.

Extracorporeal Shock Wave Lithotripsy (ESWL)

If your kidney stone won't pass naturally or can't be dissolved with medications, you may be a good candidate for ESWL. This noninvasive procedure safely and effectively "shatters" your stone without surgery, using an energy source outside your body. For this procedure, you lie in a comfortable position on a water cushion and your doctor focuses the shock waves directly at your stone. With pinpoint accuracy the shock waves hit your stone, making it crumble into sand-like particles, which then pass easily through your urinary tract. It may take more than one ESWL procedure to ensure fragmentation; or you may need an additional procedure, such as the insertion of a tube "stent" in the ureter to help passage of larger stones, before ESWL can be done.

Shockwaves from an energy source travel to your stone which begins to crack. The stone crumbles into fine sand after thousands of shockwaves.

Prevention for a Lifetime
If you've felt the pain of a kidney stone, you may worry that you'll have another. Removing or passing your stone starts your treatment process, but it doesn't prevent future stones. Fortunately, with your doctor's help, you can reduce your risk of forming new stones.
  1. Drink lots of water. Staying well-hydrated is the most important way to reduce your risk of future stones. Drink 12 eight-ounce glasses of water every day, two with every meal and two between meals. Try keeping a pitcher of water at your side.
  2. Follow your prescribed diet. Your doctor will tell you which foods contain the chemicals you should avoid. Your doctor may also recommend that you consult with a dietitian, who can help you plan enjoyable meals that won't put you at risk for future stones.
  3. Take your medications. If your doctor prescribes medications for your stone, you may want to write your doses and medication times on a calendar. There are several types of medications used to prevent kidney stones.
  4. See your doctor regularly. Regular visits to your doctor will help you detect new stones early and ensure that old stones are gone. Depending upon your type of stone, you may follow up every three months to once a year for a lifetime.

Notice: Information on this web site is provided for informational purposes only and is not a substitute for professional medical advice. You should not use the information on this web site for diagnosing or treating a medical or health condition. If you have or suspect you have a medical problem, promptly contact your professional healthcare provider.