They may be less common in children, but that's changing. And for kids, it can be a lifelong battle.
Four-year-old Alex Zellers may be a little guy, but he's been dealing with a very big problem.
Alex's parents say their son has had kidney stones, which have been very painful.
One stone in his kidney was the size of a golf ball. The other, in his bladder, was the size of a lacrosse ball.
"It's just like a giant dense egg. It's just a big mass," described Kate, Alex's mother.
Alex was born with a genetic disease called cystinuria.
"Your body doesn't absorb certain amino acids and that cystine accumulates and crystallizes in the urine forming stones early in life," said Dr. Greg Tasian, a pediatric urologist with Children's Hospital of Philadelphia.
Stones can cause higher risk of high blood pressure and heart attacks, as well as higher risk of fractures and loss of kidney function.
Alex's symptoms included recurring urinary tract infections and blood in his urine. There is no cure.
"You develop stones very early in life and that continues through the lifespan," said Dr. Tasian.
The stones Alex had were so large, they had to be surgically removed.
And although Alex's condition is rare, Dr. Tasian says he is seeing more and more kids with kidney stones.
The cause? A combination of factors, including kids eating more ultra processed foods, overuse of antibiotics and hotter temperatures causing dehydration.
"As the world becomes warmer through climate change, that is expected to increase the number of stones," Dr. Tasian said.
Common symptoms of kidney stones include abdominal, flank, or groin pain, blood in the urine, frequent urination, nausea and vomiting.
But experts point out that kidney stones can impact different children in different ways, making diagnosis challenging.
The three most important things you can do are: drink plenty of water, drink less sugary drinks, and decrease your salt intake.
As for Alex, while he'll always be at risk for developing stones, with careful watching and medication, they should be able to control them.
Studies show that both boys and girls are at risk of kidney stones, but they tend to happen more in teen girls.