Antibiotic resistance isn’t the only reason why you shouldn’t take unnecessary antibiotics. A recent study found that taking any five types of oral antibiotics was associated with a significantly higher risk of developing kidney stones—mineral and salt deposits that form in the kidney and must be passed through the urinary tract. Kidney stones have grown much more common over the past few decades without a clear explanation as to why, but this new study suggests it has to do with overuse of antibiotics.