As GLP‑1 medications become increasingly common for diabetes management and weight loss, questions have emerged about whether they influence the risk of developing kidney stones. Kyle Wood, M.D., MBA, associate professor in the UAB Department of Urology, explains what current evidence shows and why hydration remains essential for anyone using these medications.
What the research shows
Use of GLP‑1 medications has expanded rapidly, yet according to Wood, clinical studies have not demonstrated a clear increase in kidney stone formation among people taking them.
“GLP‑1 medications do not currently appear to directly increase kidney stone risk,” Wood said.
Wood pointed to one large observational study from the U.S. Department of Veterans Affairs that suggested a potential association but emphasized that follow‑up metabolic evaluations have not supported that finding.
“There are multiple publications evaluating 24‑hour urines of those on GLP‑1 medications compared to those not taking the medication, and they show overall no increased risks,” he noted.
Taken together, he explained, the available data do not support a direct link between GLP‑1 medications and nephrolithiasis, which is another term for kidney stones.
How GLP‑1 influences hydration
Where GLP‑1 medications can increase the risk of kidney stones, Wood said, is through changes in eating and drinking habits. Because they suppress appetite and slow gastric emptying, patients may unintentionally drink less throughout the day. At the same time, gastrointestinal side effects, such as nausea, vomiting, and diarrhea, may contribute to additional fluid loss.
“Lower fluid intake and higher fluid loss reduce urine volume, and urine volume is one of the main determinants of stone risk,” Wood explained.
Lower urine volume creates conditions in which stone‑forming molecules can crystallize more easily.
“With decreasing urine volume, the ‘bad’ molecules in urine can come together more easily and form stones,” Wood described.
Who may need to exercise caution
Some individuals may be more sensitive to dehydration‑related stone formation while using GLP-1 medications. Those with a prior history of kidney stones have a higher baseline risk, and Wood noted that several other factors may increase vulnerability.
“Those with gastrointestinal intolerance, older adults, patients who escalate doses quickly, and people taking medications that increase fluid loss — such as diuretics — may all be more prone to dehydration,” Wood said.
Patients who typically drink very little or who run chronically low urine volumes may also need to be especially attentive when starting a GLP‑1 therapy.
Staying hydrated
For patients with a history of kidney stones, GLP‑1 medications remain a safe option when hydration is prioritized.
“A prior stone history is not a reason to avoid GLP‑1 therapy,” Wood emphasized. “Patients with a history of kidney stones should be vigilant about their fluid intake.”
Meeting the American Urological Association’s recommended urine output of 2.5 liters per day generally requires around 96 ounces, or 3 liters, of daily fluid intake. Because GLP‑1 medications can make larger volumes uncomfortable, smaller, more frequent sips throughout the day may be easier to tolerate.
“Patients on these medications may need to be more thoughtful about fluid intake throughout the day as they may lose some of their hunger and thirst drive,” Wood added. “Some individuals utilize smart water bottles to help remind them throughout the day.”
What UAB clinicians are observing
At UAB, clinicians are seeing more individuals incorporate GLP‑1 medications into their diabetes and cardiometabolic care, yet that trend has not translated into higher rates of kidney stones. Despite the therapy’s widespread adoption, Wood has not observed any increase in stone formation among these patients.
“I have not noticed any increases in kidney stone cases amongst this patient population,” Wood said. “I am holding out hope that with the correction of these metabolic diseases, patients are hopefully less likely to form kidney stones.”
He added that while GLP‑1 medications do not appear to raise stone risk, some other weight‑loss strategies do.
“Another weight‑loss strategy — malabsorptive bariatric surgery such as Roux‑en‑Y gastric bypass — is clearly linked to increased kidney stone risk,” Wood explained. “The significant increase in risk is driven primarily by enteric hyperoxaluria, reduced urinary citrate, and lower urine volume.”
As clinicians continue to monitor outcomes, Wood emphasized that hydration remains one of the simplest and most effective ways for GLP‑1 users, especially those with a history of stones, to support kidney health.