Can Drinking Too Much Tea Damage Your Kidneys? Here’s What Expert Says

Tea is one of the most widely consumed beverages globally — beloved for its comforting warmth, antioxidant content, and potential health benefits. But what happens if you drink a lot of tea every day? Can that habit actually harm your kidneys? Experts say the answer isn’t a flat “yes” or “no,” but depends on how much, what type, and your individual health — especially your kidney health.

The Basic Science: Oxalates and Kidney Stress

One of the main concerns around excessive tea consumption — particularly black tea — is its oxalate content. Oxalates are natural compounds found in many plant-based foods and drinks, including tea. When consumed in high amounts, oxalate can bind with calcium in urine and form calcium oxalate kidney stones, a common type of kidney stone.

Tea contains enough oxalate that very large amounts — especially multiple cups of strong black tea — can increase the risk of stone formation in people predisposed to them.

How Much Tea Is “Too Much”?

Moderate tea consumption — often defined as 2–3 cups a day — is generally safe for most people and even linked to positive health effects in many studies. Drinking tea in moderation does not appear to cause kidney damage in healthy individuals.

Where it becomes a concern is with very high intake, such as 6–8 cups per day, or more — especially of high-oxalate black tea — which may raise the risk of kidney stone formation. Some case reports have even described rare outcomes related to extremely high tea consumption.

Rare But Serious Cases

There are documented rare cases where extremely high tea consumption was linked to severe kidney problems. For example, in one unusual case, a person who reportedly drank around 16 cups of iced tea per day developed kidney failure attributed to the enormous oxalate load, requiring long-term medical treatment.

Such cases are the exception rather than the rule, but they highlight that overconsumption far beyond typical amounts can negatively affect kidney health.

Other Factors That Can Increase Kidney Risk

Aside from oxalates, other aspects of tea drinking may influence kidney stress:

• Caffeine and diuretic effects: Tea contains caffeine, a mild diuretic that increases urine production. While this doesn’t directly damage kidneys, if you drink large amounts of tea without balancing fluid intake, it could contribute to dehydration and strain the kidneys.
• Added ingredients: Packaged teas or tea drinks with high sugar or additives can contain phosphorus and sodium, which people with existing kidney disease are advised to limit.
• Individual health status: People with prior kidney stones, chronic kidney disease (CKD), or a history of stones may be more sensitive to high oxalate and caffeine intake.

Is Tea Always Bad for Kidneys?

No — and that’s an important point.

• Moderate tea consumption provides antioxidants and is linked to potential health benefits like improved cardiovascular and metabolic health.
• Not all teas are equally risky. Green and herbal teas often contain fewer oxalates than black tea and are generally less associated with stone formation.
• Adequate hydration — especially drinking plain water along with tea — helps flush excess compounds and supports kidney function.

Bottom Line

• Moderation is key: For most healthy people, having a few cups of tea a day is safe and healthy.
• Watch the amount: Regularly drinking very large quantities of tea — especially black tea with high oxalate — may increase the risk of kidney stones or kidney stress in susceptible individuals.
• Balance fluids: If you’re a heavy tea drinker, make sure you also drink plenty of water and consider mixing tea types to reduce oxalate exposure.
• Consult a doctor: People with history of kidney stones or kidney disease should discuss tea consumption and diet with a healthcare professional.

Dr Kristin George, Consultant – Nephrologist and Renal Transplant, Aster Whitefield Hospital