How Long Does It Take to Pass a Kidney Stone?

Passing a kidney stone can be incredibly painful. Kidney stones are hard, crystal-like masses that typically cause spasms of pain in the lower back, side and groin and blood in the urine. Some kidney stones will pass on their own and some require removal by a doctor. The timing of passage and the likelihood of a stone passing on its own depend on its size and location.

Time for Passing a Stone

Smaller stones and those farther along the urinary tract -- closer to the bladder than to the kidneys -- are more likely to pass on their own and tend to pass more rapidly. According to the American Urological Association, the time to pass stones located in ureters -- tubes leading from the kidneys to the bladder -- is an average of 8 days for stones less than 2 mm, 12 days for stones between 2 and 4 mm and 22 days for stones between 4 and 6 mm 2. Most kidney stones that pass on their own do so by 40 days. Medications called antispasmodics may be prescribed to help a stone pass. They relax the ureters, which can increase the likelihood of passing a stone and speed up passage by 5 to 7 days, according to an article in the December 2011 issue of the “American Family Physician. 3”

When a Stone Requires Removal

Waiting for a kidney stone to pass is not appropriate for everyone. According to the American Urological Association, stone removal may be required if a stone does not pass on its own within 2 months, or if certain complications arise while waiting to pass the stone 2. These complications include decreased kidney function, ureter blockage causing a kidney infection or uncontrolled nausea, vomiting or pain.