Everything You Need to Know About Kidney Stones

A kidney stone is a hard, pebble-like deposit that forms in the kidney. It can be as tiny as a grain of sand or as large as a pearl—some are even as big as golf balls. The smaller ones will pass out harmlessly in your urine, but the bigger ones can get stuck in the ureter, bladder, or urethra, blocking the flow of urine and causing extreme pain.

What is it made of? There are many kinds of kidney stones, but the most common type is made up of calcium. You get calcium through your diet, and what your body doesn’t use for teeth and bones goes into the kidneys, where it is flushed out with urine. Occasionally, however, little bits of calcium bond with other waste products in the kidney to create a stone. People who have gout or urinary infections may also form kidney stones from excess uric acid or magnesium.

Who gets them? Though anyone can develop kidney stones, they are more common in men than women, and appear most frequently between ages 20–40. Your risk increases if you don’t drink enough fluids, you’re overweight, suffer from recurrent urinary tract infections, or have a family history of kidney stones. And unfortunately, once you get one kidney stone, you are more likely to get others in the future.

What does it feel like? If you have a big kidney stone, you will experience extreme, sharp pain in the side or back that doesn’t go away even if you change positions. You may also have fever, chills, and nausea. Your urine can be bloody or cloudy and burning.

How do you get it out? If you’re lucky, your kidney stone will eventually get flushed out with your urine, though it can be very painful as it makes its way through your urinary tract. If it’s too big to make it out on its own, you will have to undergo treatment to either break up the stone into smaller pieces (via a machine that sends shock waves into your body) or remove it via surgery.

How can I prevent them? Stay at a healthy weight, manage any chronic health conditions, and drink lots of fluids (water is best). If you’re at high risk for forming kidney stones, your doctor can prescribe medication to prevent calcium and magnesium stones from forming.