Does coffee cause kidney stones? It’s a question that pops up often, especially among health-conscious coffee drinkers trying to balance their love for caffeine with long-term wellness.
Coffee is one of the most consumed beverages worldwide, but kidney stones are also alarmingly common (they occur in 1 in 11 people) [1].
This article takes a clear, research-backed look at the relationship between coffee, caffeine, and kidney stone risk.
Does Coffee Cause Kidney Stones?
Current research suggests the answer is no, at least not in healthy individuals. In fact, coffee might have the opposite effect.
Several studies show that moderate coffee consumption is not linked to an increased risk of kidney stones and may even reduce your chances of developing them.
Why? The key lies in coffee’s natural diuretic effect, which increases urine output.
Higher urine volume helps the kidneys flush out excess minerals and waste before they have a chance to crystallize into stones.
This extra flow may be enough to reduce your overall risk, especially when paired with a well-hydrated lifestyle.
Studies On The Effect of Coffee On Kidney Stones
A 2021 study by the National Kidney Foundation found that increasing caffeine intake, even by just half a cup per day, was associated with a nearly 40% reduced risk of developing kidney stones [2].
A 2022 systematic review and meta-analysis echoed this, concluding that higher caffeine consumption was consistently linked to a lower risk of kidney stone formation [3].
Of course, this doesn’t mean that drinking coffee all day, every day is the answer. Like most things in nutrition, moderation matters.
How Coffee May Influence Kidney Stone Risk
While the overall data points toward a protective effect, it’s still worth understanding how coffee interacts with the body’s stone-forming systems.
1. Mild Diuretic Effect
One of the most immediate effects of caffeine is increased urination. Coffee works as a mild diuretic, encouraging the body to expel more fluid through the kidneys.
This may sound dehydrating at first, but studies show that moderate caffeine intake does not cause significant fluid loss when consumed as part of a normal diet [4].
Instead, that increased urine flow can be a protective mechanism. The more fluid your kidneys filter, the less concentrated your urine becomes. And when urine is diluted, minerals are less likely to clump together into crystals, which is how most stones begin.
In other words, coffee helps flush the kidneys more frequently, which may prevent waste products from accumulating into larger formations.
2. Citrate Production
Another important protective factor is urinary citrate, a substance that helps prevent stones from forming by binding with calcium in the urine [6].
When citrate is present, it makes it harder for crystals to stick together and grow.
Some evidence suggests that coffee may help increase citrate levels in the urine, especially in people who don’t get enough through diet alone [7].
This boost in citrate could further reduce the likelihood of forming calcium-based stones, which are the most common type by far.
3. Calcium & Oxalate Excretion
High concentrations of either in the urine can increase your risk of developing calcium oxalate stones, the most common type. Some people worry that coffee might raise levels of one or both, but current research doesn’t support this concern for most individuals.
Coffee does contain small amounts of oxalates, and it may have a minor impact on urinary calcium excretion [5].
However, these effects appear to be negligible in the context of a balanced diet and moderate coffee intake. For most people, the diuretic and citrate-promoting long-term effects of drinking coffee outweigh any small increases in excreted minerals.
With that said, in people who already have hypercalciuria (excess calcium in urine) or oxalate sensitivity, very high caffeine intake may need to be monitored. If you’ve had kidney stones in the past and were advised to follow a low-oxalate diet, speak with your doctor before making coffee a daily habit.
4. Caffeine Metabolism
Caffeine itself is filtered through the kidneys and processed in the liver. While this is normal, excessive caffeine intake, especially over 400 mg per day, may affect kidney filtration and blood pressure in some individuals [8].
This level would be the equivalent of 4 to 5 cups of strong coffee — well beyond what’s considered moderate.
For most healthy adults, however, a few cups per day falls within safe limits and may even be beneficial.
Is Caffeine Linked to Kidney Stones?
Coffee and caffeine often get lumped together in conversations about kidney health, but they’re not the same thing.
While moderate coffee consumption has been shown to reduce the risk of kidney stones for most people, excessive caffeine intake from a range of sources may have more complicated effects.
To understand the bigger picture, it helps to separate caffeine itself from the beverages that contain it and to take a closer look at how those choices may affect your kidneys over time.
Caffeine vs. Coffee: Not All Sources Are Equal
Caffeine is a naturally occurring stimulant found in coffee, tea, cocoa, and certain soft drinks. When consumed in reasonable amounts, it can boost alertness, improve focus, and, in the case of coffee, may even help flush out the kidneys by increasing urine output.
But not all caffeinated drinks offer the same benefits.
Coffee contains beneficial compounds like antioxidants and polyphenols, and studies have repeatedly shown that coffee on its own, even when caffeinated, does not raise the risk of kidney stones [9].
The issue arises when caffeine is consumed in much higher doses, or from sources that introduce other risk factors, like high sugar content or chemical additives — energy drinks and other common sodas.
Other Sources: Soda & Energy Drinks
Sodas, energy drinks, and sweetened teas often carry more caffeine than people realize, and they also come with a side of sugar, phosphoric acid, and artificial ingredients that may strain the kidneys.
Cola Flavored Drinks
Take cola-flavored soft drinks as an example. They’re a common source of both caffeine and phosphoric acid, which can contribute to the formation of calcium phosphate stones, a less common but still significant type of kidney stone.
Energy Drinks
Many energy drinks like Monster pack twice as much caffeine per serving as a cup of coffee, and unlike classic cold-brewed coffee, they’re often loaded with sweeteners, sodium, and herbal additives that can alter hydration balance or mineral excretion.
While the caffeine content in these drinks isn’t always the main issue, the overall formula creates conditions that may increase the risk of kidney stone formation.
Black Coffee
In contrast, plain black coffee or concentrated black espresso without added sugar or cream is typically much gentler on the kidneys, especially when consumed alongside a well-hydrated diet.
High Doses: What Happens with Too Much Caffeine?
Moderate caffeine intake, generally considered around 200 to 300 mg per day (roughly 2–3 cups of coffee), is not linked to kidney stone risk for most healthy adults.
However, when daily intake climbs to 400 mg or more, some changes can occur:
- Increase in Urinary Calcium — High-dose caffeine has been shown to increase calcium excretion in the urine [10]. While this doesn’t automatically lead to kidney stones, it may be problematic for people with conditions like hypercalciuria or those who’ve had calcium-based stones in the past.
- Altered Filtration Rates — Very high levels of caffeine may affect how efficiently the kidneys filter waste, especially in people with high blood pressure or other kidney-related conditions [11].
- Increased Dehydration Risk — Although moderate caffeine doesn’t cause dehydration in healthy individuals, heavy intake without adequate water may shift the body’s fluid balance and reduce urine volume, increasing the concentration of stone-forming minerals [12].
So while caffeine itself isn’t dangerous in moderate doses, more isn’t always better. If you’re drinking six or more highly caffeinated beverages a day, it may be worth rethinking your routine, particularly if you’ve had kidney stones before.
Common Kidney Stone Symptoms to Watch For
Even with a healthy diet, kidney stones can still develop, and knowing the early signs is key. While not every twinge in your back is cause for concern, these symptoms are worth paying attention to, especially if they come on suddenly or get worse over time.
Here are the most common kidney stone symptoms to watch for [13]:
- Sharp or Severe Pain — In the side, lower back, or groin.
- Painful Urination — Often described as burning or stinging.
- Blood in the Urine — May appear pink, red, or brown (see a doctor immediately).
- Nausea and Vomiting — Especially during intense pain episodes.
- Frequent or Urgent Need to Pee — Even when little urine comes out.
These symptoms often appear when a stone moves through the urinary tract and becomes temporarily stuck, causing pain, pressure, and inflammation.
If you experience any of the above, especially in combination, it’s important to contact a doctor right away. Kidney stones can vary in size, and while many pass on their own, others require medication or medical intervention.
You should also seek immediate care if you notice:
- Fever and Chills — May signal infection.
- Ongoing Vomiting — Inability to keep fluids down.
- Blood in the Urine — That doesn’t resolve (see a doctor immediately).
- Inability to Urinate — Feeling like you can’t fully empty your bladder.
- Severe Pain — Prevents you from sitting still or getting comfortable.
These may point to a more serious blockage, infection, or larger stone that won’t pass on its own, and could lead to complications if untreated.
How Much Coffee Is Safe for Kidney Health?
For most people, moderate coffee intake is not only safe but potentially beneficial for kidney function. Still, there are some important considerations around quantity, hydration, and personal risk factors.
Here’s what you need to know about drinking the best healthy coffee wisely if you’re thinking about your kidneys:
Safe Intake for Most People
For healthy adults with no history of kidney stones or kidney disease, 1 to 2 cups of coffee per day is considered safe and possibly protective.
Multiple studies have shown that this level of intake may help reduce the risk of chronic kidney disease (CKD), thanks to coffee’s antioxidant and anti-inflammatory properties [14].
A large-scale 2022 study found that people who drank two or more cups of coffee daily had a lower risk of developing CKD compared to those who drank none [15].
Another analysis of over 500,000 people showed a dose-response effect, where each additional cup of coffee lowered the risk slightly more [16].
Hydration Still Matters
Kidney stones often form when the body isn’t flushing out waste properly, and the best prevention strategy is to stay well-hydrated.
Still, water should remain your primary beverage. If you’re drinking coffee throughout the day, try to match each coffee cup with a glass of water, especially in hot weather or after exercise, when fluid loss is higher.
People who rely too heavily on caffeinated drinks without enough water may unintentionally reduce urine volume, leading to more concentrated urine — a known risk factor for kidney stone formation.
Who Should Be More Cautious?
While moderate coffee consumption is safe for most people, certain health conditions require more personalized guidance.
That includes individuals with:
- Calcium Oxalate Stones — These are the most common kidney stones, and while coffee doesn’t dramatically affect oxalate levels, people with a history of these stones may need to watch caffeine intake more closely.
- Chronic Kidney Disease (CKD) — People with early-stage CKD can usually tolerate some caffeine, but should stay under three cups per day and monitor how coffee fits into their overall potassium and fluid intake.
- Advanced Kidney Disease or Dialysis Patients — In these cases, fluid restrictions may apply, and coffee might need to be limited along with all beverages.
- Kidney Transplant Recipients — Post-transplant guidelines often recommend limiting caffeine to reduce stress on the new kidney and avoid medication interactions.
If you fall into any of these groups, it’s best to consult your nephrologist or healthcare provider to get personalized advice.
Watch for Hidden Potassium
One 8-ounce cup of black coffee contains about 116 mg of potassium, which is manageable for most people, but that number can rise quickly if you add milk, creamers, or flavoured syrups.
Excess potassium can lead to muscle weakness, heart rhythm problems, or even cardiac arrest in severe cases [17].
If you’re drinking multiple cups of coffee and pairing them with high-potassium foods (like bananas or avocado toast), you may unknowingly spike your daily intake.
A registered dietitian can help you plan coffee consumption that fits safely into a kidney-friendly diet, especially if you have stage 3 or higher CKD.
Slow Caffeine Metabolizers May Need Less
Your genes can also influence how your body handles caffeine. People with a genetic variant in the CYP1A2 gene metabolize caffeine more slowly, meaning it stays in the body longer and may have a stronger effect on blood pressure and kidney filtration [18].
One study showed that people with this gene variant who also had high blood pressure and consumed high levels of caffeine were more likely to develop kidney complications [18].
If you notice symptoms like jitteriness, anxiety, or difficulty sleeping even after a small amount of coffee, you may fall into this category.
What to Remember About Coffee and Kidney Health
Coffee has long been misunderstood when it comes to kidney health. But modern research paints a much more balanced, and often positive, picture.
For most people, the answer to “does coffee cause kidney stones?” is a clear no. Coffee may help reduce your risk when consumed in moderation.
Here’s what to remember about coffee and kidney health:
- 1 to 2 cups a day is safe for the majority of people, and may even protect against kidney disease.
- Hydration is key — coffee can help, but water still matters most.
- People with kidney conditions should talk to their doctor about safe limits.
- Excessive caffeine, especially from sodas or energy drinks, may do more harm than good.
- Potassium and fluid balance matter in kidney disease, so watch your add-ins and total intake.
Your kidneys work hard every day, and the right habits can make their job easier.
FAQs: Does Coffee Cause Kidney Stones
People often have questions about the connection between coffee, hydration, and kidney stone risk.
Below are quick, clear answers to some of the most common concerns…
1. What Drinks Cause Kidney Stones the Most?
Drinks high in sugar and additives, like colas, sweet iced teas, and many energy drinks, are most commonly associated with a higher risk of kidney stone formation.
2. What Triggers Kidney Stones?
Kidney stones can develop when your body doesn't flush out minerals properly, often triggered by low fluid intake, too much sodium, or diets rich in oxalates.
3. What Drink Removes Kidney Stones?
Plain water is your best defense, but adding lemon or citrus can help raise citrate levels in your urine, which makes it harder for stones to form.
4. Is Coffee Bad for Uric Acid?
Not necessarily, moderate coffee consumption has been shown to slightly lower uric acid levels in some people, especially those without underlying health issues.
5. What Is the Best Morning Drink for the Kidneys?
Start your day with plain water or lemon water to support hydration, kidney function, and natural detoxification.
6. Does a Lack of Water Cause Kidney Stones?
Yes, when you’re dehydrated, urine becomes more concentrated with minerals, which increases the chances of those minerals crystallizing into stones.
7. What Color Is Urine When Your Kidneys Are Failing?
Urine may turn dark brown, reddish, or appear foamy when kidney function declines — often a sign that proteins or blood are leaking into the urine.
8. How to Stop Kidney Stones from Forming?
Drink plenty of fluids daily, lower your salt and animal protein intake, and eat more fruits and vegetables to support natural kidney balance.
9. Who Is More Prone to Kidney Stones?
You're more likely to develop stones if you have a family history, don’t stay hydrated, or follow a high-sodium, high-protein diet, especially with low physical activity.
10. How Long Do Kidney Stones Last?
Smaller stones may pass within a few days with hydration, but larger stones can take weeks and sometimes require medical treatment or removal.
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- Zhao, J., Huang, Y., & Yu, X. (2022). Caffeine intake and the risk of incident kidney stones: a systematic review and meta-analysis. International Urology and Nephrology.
- Lohsiriwat, S., Hirunsai, M., & Chaiyaprasithi, B. (2011). Effect of caffeine on bladder function in patients with overactive bladder symptoms. Urology Annals, 3(1), 14.
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- Thakore, P., & Liang, T. H. (2023, June 5). Urolithiasis. PubMed; StatPearls Publishing.
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- Geng, J., Qiu, Y., Kang, Z., Li, Y., Li, J., Liao, R., Qin, Z., Yang, Q., & Su, B. (2022). The association between caffeine intake and risk of kidney stones: A population-based study. Frontiers in Nutrition, 9.
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