Smoking Impact on Kidney Stone Passage Rates

A fascinating study out of Turkey looked at how smoking, specifically nicotine, affects the passage of kidney stones in the lower ureter. The results showed that smokers had significantly lower stone passage rates—especially for stones between 8 and 10 mm in size. I break down what this means, how the study was structured, and what you should consider if you're a smoker dealing with kidney stones.

Key Takeaways:

• Smoking may reduce kidney stone passage success—especially with larger stones.

• For stones 8–10 mm, non-smokers passed stones, smokers didn’t.

• Passage rates were similar for stones under 8 mm, regardless of smoking.

• The study suggests a 21% higher passage rate in non-smokers for stones over 4 mm.

 I came across a study from Turkey that really caught my attention.

It explored the smoking impact on kidney stone passage, and more specifically, it asked whether nicotine affects stone passage rates in the lower portion of the ureter.

That’s right—they weren’t just looking at general health. They wanted to see what role nicotine might play in the actual ability to pass a stone naturally.

And the results were pretty surprising.

What They Studied

Researchers looked at 88 patients with stones under 10 mm. They were split into two groups: smokers and non-smokers.

Everyone had stones located in the distal ureter, which is the lower part closer to the bladder. And here’s an important note:

None of the patients were on alpha blockers.
These are drugs like Tamsulosin that are often used to increase the chance of stone passage. By removing that variable, the researchers could focus solely on smoking’s impact.

Now here’s where it gets interesting…

Does Smoking Help or Hurt Peristalsis?

The researchers were curious because in animal studies (specifically in dogs), nicotine was shown to increase peristalsis.

Peristalsis is the contraction and relaxation movement your ureter uses to help push a stone out. If nicotine increased peristalsis in dogs, could it do the same in humans?

You might expect better passage rates in smokers if that were true.

But that’s not what they found.

What the Data Showed

Let’s break it down by stone size and group results.

1–4 mm Stones
Passage rates were nearly identical for both groups.

• Smokers and non-smokers passed stones at roughly the same rate

• Differences were negligible and likely due to sample size

4–8 mm Stones
Still pretty even here.

• Around 60–65% of stones passed

• Smoking status didn’t seem to make much of a difference

But then things changed dramatically…

8–10 mm Stones
This is where the gap became undeniable.

• 0% of smokers passed their stones

• 80% of non-smokers passed theirs

That’s a massive gap—and not something you can ignore.

A Quick Note on the Study Type

Before we get too carried away, I want to be clear: this was an epidemiological study.

That means it was observational. No interventions were made. No controlled experiments. They simply watched what happened and recorded the results.

So while this doesn’t prove that smoking causes poor passage rates, it strongly suggests a correlation—and one worth paying attention to.

Let’s Talk Guidelines

If you’ve been to the ER with a kidney stone recently, you’ve probably heard about the 5 mm rule.

In the U.S., 5 mm is the tipping point between being sent home with medication like Tamsulosin or being recommended for surgical intervention.

So when a study starts to show differences in passage rates above and below that 5 mm mark, it matters.

Here’s how the numbers looked:

• Stones under 5 mm passed about 68% of the time (very close to what the American Urological Association reports—around 80%)

• For stones over 4 mm, smokers passed 46%, while non-smokers passed 67%

• That’s a 21% advantage in favor of non-smokers

And remember, for stones between 8–10 mm, not a single smoker in the study passed their stone. That stat alone is hard to shake off.

What This Means If You’re a Smoker

Now I’m not here to tell anyone how to live their life. But if you’re someone who suffers from kidney stones—and especially if you’re currently trying to pass one—this information is worth thinking about.

The smoking impact on kidney stone passage might be the difference between passing a stone at home or ending up in surgery.

Even if you’ve smoked for years, any positive change now could potentially improve your body’s ability to pass stones naturally—especially the larger ones.

My Personal Takeaway

I’ve talked to hundreds of people who deal with kidney stones, and I always say: every little edge helps.

You already know how brutal this process can be.

If cutting back or quitting smoking could boost your stone passage success—especially by 20% or more—why not stack the odds in your favor?

This study was small, and yes, it was observational. But it revealed a massive difference that could very well reflect how smoking affects the muscles and tissues in your urinary system.

And while nicotine might improve muscle movement in animals, it clearly doesn’t seem to help us get stones out faster.

Final Thoughts

To recap:

• Smoking may seriously reduce your ability to pass kidney stones, especially those larger than 8 mm

• Non-smokers passed 80% of large stones compared to 0% of smokers

• Even for mid-sized stones (4–8 mm), non-smokers had higher passage rates

• The biggest takeaway? Your lifestyle choices may directly impact stone outcomes

So if you’re battling a stone and you’re a smoker—now might be the perfect time to re-evaluate.

I’d love to hear your experience. Have you passed stones as a smoker? What changed if you quit? Let’s keep the conversation going.