Does Tea Cause Kidney Stones? Understanding the Link Between Your Brew and Renal Health

Kidney stones are common and often excruciatingly painful. It affects millions of people worldwide. There are many factors that contribute to their formation—including genetics to hydration—diet is often an overlooked factor which in reality plays a significant role. Among the various dietary components, tea frequently comes under the spotlight. Why? Because it is a beverage that is enjoyed by millions of people. But does tea cause kidney stones? It all boils down to one thing, its oxalate content. Oxalate is a naturally occurring compound that is present in many plants. It is one of the things that contribute to the formation of stones. It is primarily a component of the most prevalent stone called—calcium oxalate.

So, does tea actually cause kidney stones? This has triggered many debates among researchers, tea-enthusiasts, and health-conscious people alike. The answer, however, is not just a simple yes or no. The relationship between the two is somewhat complex. It involves the tea type, brewing method, individual susceptibility, and even your hydration level play a part. This particular picture is subtle. This article aims to help you understand the complex relationship between kidney stones and kidney health. It also aims to give expert opinions and practical advice so you can still enjoy your favorite brew while protecting your kidneys. We will explore what oxalates are, differentiate various tea types and their impact, and provide actionable strategies to minimize any potential risks. It ensures that you have adequate knowledge so you can make informed choices about your overall health.

Key Takeaways

• Tea contains oxalates , which is a component of the most common type of kidney stones (calcium oxalates)

• The impact of tea on kidney stone risk is complex, which depends on the type of tea, brewing method, or individual risk factors

• Black tea generally has the highest oxalate content, while green, white, and most herbal teas have lower levels

• Moderate tea consumption, for most people, especially when combined with adequate fluid intake, does not significantly increase the risk for kidney stones

• Studies suggest that green tea may have protective effects against stone formation

• Iced tea poses the highest risk because it has the concentrated oxalate levels and added sugar

• Hydration is an important factor for kidney stone prevention; the fluid intake from tea may be beneficial

• People with a history of kidney stones or hyperoxaluria should consult their doctor or dietician for personalized advice

• Practical tips to minimize the risk include choosing teas with lower oxalate levels, shorten brewing time, and drinking tea along with calcium-rich foods

What is the Relationship Between Tea Consumption and Kidney Stone Formation?

The relationship between drinking tea and kidney stone formation is more intricate than you think. It is not just a simple visualization of cause and effect. While it is true that the tea contains oxalates, moderate consumption for most people won’t make them develop kidney stones. Oxalate, being a major contributor to kidney stones, does not automatically make you develop them. In fact, some studies have shown that the fluid intake from tea may even be beneficial in preventing stones. Adequate hydration is key to stone prevention. The key concept to understand here is the balance between oxalate content, hydration, and whether you are prone to developing kidney stones.

How Do Oxalates in Tea Contribute to Kidney Stones?

Oxalates, which may be in the form of oxalic acid, are naturally occurring. Meaning, they are found in many plants, which include tea leaves. When oxalates, present in food and beverage, are consumed, they bind with calcium in the urine to develop calcium oxalate crystals. These crystals then can stick to each other and grow into bigger stones. Calcium oxalate is the most prevalent type of kidney stones, which makes up about 80% of all cases.

However, just consuming oxalate in tea does not automatically mean you are going to develop kidney stones. The amount of oxalate you are absorbing from food and beverages, which is known as oxalate bioavailability, varies significantly. For example, if you eat calcium-rich foods or drink calcium-rich beverages along with oxalate-rich ones, you could actually reduce oxalate absorption. The calcium binds to the oxalate in your gut before it can even be absorbed in the blood. This is the reason why you should consider adding milk to tea. Because it is a simple way to prevent some of the oxalate concerns.

Also, different types of tea contain different levels of oxalate. In general, black tea contains the highest oxalate. This is followed by the following:

• Oolong

• Green

• White teas

• Herbal teas

For example, a cub of black tea can contain about 3.0-15.6  mg of oxalate. Green tea, on the other hand, may contain 0.8-14 mg/100 mL. But, of course, this depends on the brewing method and the variety you have on hand. It is important to remember that these are soluble oxalates. And, their actual impact on stone formation depends largely on how much of the oxalate gets into the blood and how much water or fluid you have consumed alongside them.

Does Hydration from Tea Help Prevent Kidney Stones?

The key to preventing kidney stones is for you to stay hydrated. This means, you need to drink enough water to dilute your urine. Doing so would make it hard for minerals like calcium and oxalate to bind together and form stones. The National Kidney Foundation emphasizes that one of the simplest and most effective methods of keeping kidney stones away is to drink plenty of water.

Tea is primarily water, which means it can significantly contribute to your daily fluid intake. For many people, the hydrating benefits that they get from drinking tea can outweigh the potential risks associated with its oxalate content. This is especially true if it is consumed in moderation. The reason for this is that there is increased fluid volume, which helps flush the kidneys. This results in the reduction of concentration of stone forming substances. So if you enjoy tea and keep good overall hydration, tea may even be part of a kidney-stone preventing diet.

Which Types of Tea Have the Highest and Lowest Oxalate Content?

Not all teas are created equal. Oxalate content varies significantly by type and preparation.

So, understanding the oxalate content of different teas is important if you are concerned about kidney stones. While all true teas (those that are derived from Camellia sinensis) contain oxalates, the amounts vary significantly depend on which tea we are talking about including:

• Type of tea

• Processing methods

• Brewing techniques

Generally, darker teas tend to have higher oxalate content than light-colored ones.

To give an overview of the types of tea, here is a table simplified for you:

Is Black Tea a Major Risk Factor for Kidney Stones?

Black tea contains the highest levels of oxalate among common tea varieties. It undergoes full oxidation during processing. This led to a common belief that black tea is a significant risk factor for developing kidney stones. But this is not applicable to everyone. Scientific studies have provided a more subtle picture than originally believed. While black tea contributes to your dietary oxalate consumption, its impact on kidney stone formation is not as simple as correlating the content with the risk.

For example, there is a study where it examined the effect of black tea consumption on urinary risk factors for the formation of kidney stones. It found no significant increase in the risk, particularly among normal subjects. It is supported by another study, which found out that drinking a lot of black tea did not increase the levels of calcium oxalate particularly in the urine of healthy men. This means that the body’s ability to absorb and process oxalates, combined with good overall fluid intake, have played a more crucial role than just the concentration of oxalate in teas. Generally, if you consume black tea moderately, it is highly unlikely that it is a major risk factor to develop kidney stones. In fact, drinking tea has decreased the risk of stone formation by 14%. So the key here is moderation and making sure that you take sufficient fluid to dilute common stone-forming substances.

Can Green Tea Help Prevent Kidney Stones?

As opposed to black tea, green tea undergoes minimal oxidation, considering its lower oxalate content. Several studies suggest that green tea actually offers protective benefits against kidney stones. The protective effect is often owed to its lower oxalate levels but also to its antioxidant properties. It contains epigallocatechin gallate (EGCG), which may prevent the aggregation of calcium oxalate. More than protection against kidney stones, green tea consumption is also associated with lower risk of developing dementia.

Research has shown promising results about green tea’s role in preventing kidney stone formation. One study found that for each cup of tea daily, women have a reduced risk of kidney stone formation by 8%. This is supported by another study that found green tea treatment has decreased the excretion of oxalate in the urine and thereby decreased the formation of calcium oxalate. So what does this imply for you? This evidence suggests that drinking green tea can be very beneficial as a beverage if you want to reduce the risk of forming kidney stones. The catch is just to drink it on a daily basis, which can be good if you’re an avid drinker.

What About Herbal Teas, Oolong, and White Tea?

More than black and green tea, there are also other tea varieties that may be a cause of concern for its oxalate profile. This is true if you are conscious about kidney stones and its impact on your kidney health:

• Herbal teas

Most herbal teas such as peppermint, ginger, chamomile, and rooibos are not from the common Camellia sinensis plant. They generally contain very low to negligible amounts of oxalates. You can choose these teas as alternatives if you are concerned about oxalate content. These contribute to hydration without adding much oxalate load. They are safe and often recommended for kidney stone prevention.

• Oolong Tea

This is a semi-oxidized tea, which places its oxalate content between green and black tea. Like green tea, it is still considered lower in oxalate level than black tea. This means that it can be a suitable alternative if you don’t want oxalate in your tea. Studies often include oolong along with green tea in terms of potential benefits for kidney health.

• White Tea

This is the least processed of all true teas and it is made from young tea leaves and buds. The oxalate content of this tea is very low, which may be similar or lower than the green tea. It is, therefore, a good alternative tea for people looking to reduce oxalate intake while still being able to sip their favorite brew.

Is Iced Tea More Likely to Cause Kidney Stones?

Yes—iced tea can be more problematic. Large volumes of strong iced tea mean more oxalates in one sitting. Commercial iced teas often contain added sugars, which increase stone risk due to altered urine composition.

Fructose, in particular, can elevate calcium, oxalate, and uric acid levels in urine. If you love iced tea, go for unsweetened, lightly brewed versions, and hydrate with water alongside it.

When Should You Limit Tea Intake?

Consider limiting or modifying your tea habits if:

• You have recurrent calcium oxalate stones.

• You’re diagnosed with hyperoxaluria.

• You consume high-oxalate foods in excess.

• You’re prone to dehydration.

Consulting a nephrologist or renal dietitian can provide personalized recommendations to manage your kidney stone risk effectively.

How to Enjoy Tea While Protecting Your Kidneys

Here’s how you can keep drinking tea while minimizing stone risks:

• Choose low-oxalate teas: Green, white, and herbal.

• Steep for shorter durations: Less time = fewer oxalates.

• Avoid strong or concentrated brews: Dilute when possible.

• Pair tea with calcium-rich foods: Cheese, milk, or yogurt.

• Stay hydrated throughout the day: Aim for 2–3 liters of fluid.

General Dietary Tips for Kidney Stone Prevention

• Hydrate consistently: Clear or light-yellow urine is a good sign.

• Limit sodium: High salt increases calcium in urine.

• Eat more fruits & veggies: Especially citrus fruits for citrates.

• Moderate animal protein: Excess can increase stone-forming substances.

• Cut added sugars: Especially high-fructose drinks and snacks.

Final Thoughts

Tea does not really cause kidney stones, but the context behind this matters. While black tea contains oxalates, it does not automatically mean you are going to develop one just because you drink it. Like mentioned, context matters. If you are keeping your hydration levels up, drinking tea should not be a cause to worry. Green, white, and herbal teas offer lower-risk options. And smart strategies like adding milk or steeping tea for less time can further minimize risks.

It all boils down to balance. Maintain proper hydration, make thoughtful dietary choices, and consult a healthcare professional if you're at high risk. With these precautions, you can keep sipping your favorite brew, without worrying about kidney stones.

Quick Summary Box

• Tea has oxalates, which can form kidney stones.

• Risk depends on tea type, brew strength, hydration, and personal factors.

• Black tea has the most oxalates; drink in moderation.

• Green, white, and herbal teas are lower in oxalates.

• Green tea may help prevent stones.

• Herbal teas are usually safe and low in oxalates.

• Iced tea can be risky due to strong brew and added sugar.

• Staying hydrated reduces stone risk.

• Add milk or calcium-rich foods to lower oxalate absorption.

• Limit strong brews and drink plenty of fluids.

• If you’ve had stones or have high oxalate levels, talk to your doctor.

• Tea is safe for most people when consumed smartly.

References

References

Atlantic Urology Clinics. (2025, January 16). Does Tea Cause Kidney Stones? - Atlantic Urology Specialists - Serving Myrtle Beach and the Grand Strand. Atlantic Urology Specialists - Serving Myrtle Beach and the Grand Strand. https://atlanticurologyclinics.com/blog/does-tea-cause-kidney-stones/ 

Charrier, M. J., Savage, G. P., & Vanhanen, L. (2002). Oxalate content and calcium binding capacity of tea and herbal teas. Asia Pacific Journal of Clinical Nutrition, 11(4), 298–301. https://doi.org/10.1046/j.1440-6047.2002.00294.x 

Curhan, G. C. (1998). Beverage Use and Risk for Kidney Stones in Women. Annals of Internal Medicine, 128(7), 534. https://doi.org/10.7326/0003-4819-128-7-199804010-00003 

Curhan, G. C., Willett, W. C., Rimm, E. B., Spiegelman, D., & Stampfer, M. J. (1996). Prospective Study of Beverage Use and the Risk of Kidney Stones. American Journal of Epidemiology, 143(3), 240–247. https://doi.org/10.1093/oxfordjournals.aje.a008734 

Does black tea promote kidney stone formation? - Study Summary. (2025). Examine.com. https://examine.com/research-feed/study/9K44zd/ 

How do you avoid kidney stone attacks? - Harvard Health. (2021, February). Harvard Health. https://www.health.harvard.edu/diseases-and-conditions/how-do-you-avoid-kidney-stone-attacks 

Iced Tea Increases Kidney Stone Risk: Advanced Urology Medical Offices: Urologists. (2025). Advancedurology.net. https://www.advancedurology.net/blog/iced-tea-increases-kidney-stone-risk 

ITOH, Y., YASUI, T., OKADA, A., TOZAWA, K., HAYASHI, Y., & KOHRI, K. (2005). PREVENTIVE EFFECTS OF GREEN TEA ON RENAL STONE FORMATION AND THE ROLE OF OXIDATIVE STRESS IN NEPHROLITHIASIS. Journal of Urology, 173(1), 271–275. https://doi.org/10.1097/01.ju.0000141311.51003.87 

Kaise, R., Kitamura, K., Watanabe, Y., Kabasawa, K., Takahashi, A., Saito, T., Kobayashi, R., Oshiki, R., Yamazaki, O., Watanabe, K., Takachi, R., Tsugane, S., & Nakamura, K. (2025). Green tea consumption and dementia risk in community-dwelling Japanese people aged 40–74 years: A 12-year cohort study. The Journal of Nutrition, Health and Aging, 29(8), 100615. https://doi.org/10.1016/j.jnha.2025.100615 

Nazarian, R., Lin, N., Thaker, S., Yang, R., Wong, G. C. L., & Scotland, K. B. (2025). What Causes Calcium Oxalate Kidney Stones to Form? An Update on Recent Advances. Uro, 5(1), 6. https://doi.org/10.3390/uro5010006 

Norfleet, T. (2024, March 13). What Is the Best Drink for Kidney Stones? GoodRx. https://www.goodrx.com/conditions/kidney-stones/best-drink-for-kidney-stones 

Oxalates In Tea: Concern or Not? (2023). TeaMuse. https://www.teamuse.com/article_230609.html

Rode, J., Bazin, D., Dessombz, A., Benzerara, Y., Letavernier, E., Tabibzadeh, N., Hoznek, A., Tligui, M., Traxer, O., Daudon, M., & Haymann, J.-P. (2019). Daily Green Tea Infusions in Hypercalciuric Renal Stone Patients: No Evidence for Increased Stone Risk Factors or Oxalate-Dependent Stones. Nutrients, 11(2), 256. https://doi.org/10.3390/nu11020256 

Siener, R., & Hesse, A. (2021). Effect of Black Tea Consumption on Urinary Risk Factors for Kidney Stone Formation. Nutrients, 13(12), 4434. https://doi.org/10.3390/nu13124434 

Six Easy Ways to Prevent Kidney Stones. (2024). Kidney.org. https://www.kidney.org/kidney-topics/six-easy-ways-to-prevent-kidney-stones 

Wang, H., Fan, J., Yu, C., Guo, Y., Pei, P., Yang, L., Chen, Y., Du, H., Meng, F., Chen, J., Chen, Z., Lv, J., & Li, L. (2021). Consumption of Tea, Alcohol, and Fruits and Risk of Kidney Stones: A Prospective Cohort Study in 0.5 Million Chinese Adults. Nutrients, 13(4), 1119. https://doi.org/10.3390/nu13041119 

Frequently Asked Questions

Q: Does adding milk reduce kidney stone risk?

A: Yes. Calcium binds oxalate in the gut, preventing absorption and reducing risk.

Q: Are tea bags worse than loose leaf?

A: Not necessarily. It depends more on brew strength and duration.

Q: Can decaffeinated tea cause kidney stones?

A: Yes, if it’s high in oxalates. Caffeine isn’t the primary concern, oxalates are.