We found only 2 human studies measuring what hibiscus does to urine chemistry, with 36 men in 1994 and 18 people in 2008. Their signals on kidney stone risk point in different directions.
If you have kidney stones or kidney disease, that uncertainty is the main fact, and this page sets out what is known around it.
Quick Answer: Is Hibiscus Tea Bad for Your Kidneys?
For healthy kidneys, short trials show no harm, and 1 trial found creatinine clearance improved over 4 weeks. For stones, 2 small human studies gave mixed signals; 1 found more uric acid in the urine of stone formers. With kidney disease, ask your nephrologist first, partly because of the aluminium and potassium in the tea.
Key Takeaways
- We found 2 human urine studies of hibiscus, with 36 and 18 people.
- In 1994, urinary oxalate did not change, but citrate fell.
- In 2008, stone formers excreted significantly more uric acid on 3 g daily.
- Roselle was not among 6 high-oxalate foods named in a 109-food analysis.
- Rats given a 6% infusion as their only drink showed kidney damage.
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What Is Known, in One Table
Kidney questions about hibiscus get confident answers online in both directions. The evidence underneath is small, and much of it comes from rats, so here is all of it in 1 place before any interpretation.
| Study | Who | What happened |
|---|---|---|
| 1994, Thailand | 36 healthy men, roselle juice 16 or 24 g a day | Uric acid, citrate, calcium and sodium in urine fell; oxalate did not change |
| 2008, Thailand | 9 stone formers and 9 without, 1.5 g twice daily | Uric acid excretion rose; oxalate and citrate trended up |
| 2017, Nigeria | 78 people with untreated hypertension | Creatinine clearance and urine volume rose |
| 2025, Thailand | 108 people, 1,000 mg extract daily | No kidney function change vs placebo |
| 2011 and 2012, rats | High oxalate induced chemically | Fewer calcium oxalate crystals in the kidney |
| 2026, rats | 6% infusion as the only drink | Markers of kidney damage |
For what hibiscus is and its main evidence, see hibiscus tea and what it does.
Kidney Stones: The Mixed Signal
Stone risk depends on several things in urine at once: calcium, oxalate and uric acid, which can form stones, and citrate, which protects against them. Hibiscus moved several of these, and not all in a helpful direction.
- Citrate: fell in 1994, which would raise risk.
- Calcium: fell in 1994, which would lower risk.
- Oxalate: unchanged in 1994, trending up in 2008.
- Uric acid: excretion rose in stone formers in 2008.
The 1994 study found a lower dose cut urinary salt output more than a higher one.[1]Changes in urinary chemical composition in healthy volunteers after consuming roselle (Hibiscus sabdariffa Linn.) juice — Journal of the Medical Association of Thailand (1994) View source The 2008 study gave a cup of 1.5 g twice daily for 15 days.[2]Uricosuric effect of Roselle (Hibiscus sabdariffa) in normal and renal-stone former subjects — Journal of Ethnopharmacology (2008) View source
Uric acid in urine matters most for people who form uric acid stones or have gout. For calcium oxalate stones the rat studies were encouraging, but the stones were induced chemically.[3]Effects of Orthosiphon grandiflorus, Hibiscus sabdariffa and Phyllanthus amarus extracts on risk factors for urinary calcium oxalate stones in rats — The Journal of Urology (2011) View source
Is Hibiscus High in Oxalate?
People on a low-oxalate diet often ask this first. A 2021 analysis measured oxalate in 109 foods and named the high-oxalate ones; roselle was named instead for its very high antioxidant activity, which is a different list.
- Named high in oxalate: raw spinach, chard, purslane, almonds and amaranth, among others.
- Roselle: listed among the highest antioxidant foods.
- Roselle calyces, 2026: oxalate below tolerable limits.
- Our caveat: neither study gave a figure per cup of tea.
The 2021 study also found that people with overweight exceeded the advised daily oxalate intake overall.[4]Oxalate Content and Antioxidant Activity of Different Ethnic Foods — Journal of Renal Nutrition (2021) View source
Kidney Function and Blood Pressure
High blood pressure strains the kidneys, so a drink that lowers it could help them in principle; see the blood pressure evidence. The short trials are reassuring, though none ran long enough to show protection.
- 2017 trial: creatinine clearance up over 4 weeks.
- 2024 trial: added to valsartan in mild kidney disease; renal markers no different.
- 2025 trial: no kidney change over 12 weeks.
- Long-term protection: not tested.
The 2017 trial also found more urine than with lisinopril.[5]Does consumption of an aqueous extract of Hibiscus sabdariffa affect renal function in subjects with mild to moderate hypertension? — Journal of Physiological Sciences (2017) View source The 2024 trial lasted 90 days.[6]Roselle (Hibiscus sabdariffa L.) extract as an adjunct to valsartan in patients with mild chronic kidney disease — Avicenna Journal of Phytomedicine (2024) View source
Neither trial was designed to test kidney protection over years.
When More Becomes Harmful
In 2026, healthy rats given a 6% hibiscus infusion as their only drink for 1 month showed kidney changes linked to excess hydrogen sulphide. That is a very strong brew, drunk instead of water, but it marks where more stops being better.
- 6% infusion: 60 g of calyx per litre.
- A strong trial brew: 10 g in 500 mL, or 20 g per litre.
- Duration: 1 month as the only fluid.
- Human relevance: unknown, but a reason not to drink it all day.
In those rats, the kidney blood vessels relaxed less well than normal.[7]The Chronic Elevated Consumption of Hibiscus sabdariffa Linnaeus Results in Kidney Damage Associated with Excess H2S — International Journal of Molecular Sciences (2026) View source Before raising your intake, check how much hibiscus a day is sensible.
Kidney Disease: Aluminium and Potassium
With chronic kidney disease, what the kidneys cannot clear matters. Hibiscus infusions are rich in minerals, and a 2013 analysis singled out their aluminium content for children with chronic kidney failure.
- Aluminium: up to 1.2 mg per litre of infusion.
- That study's advice: exclude it for children with chronic kidney failure.
- Urine aluminium: rose over 16 days of drinking in healthy volunteers.
- Potassium: hibiscus infusions had the highest levels among 6 herbal teas.
The aluminium and potassium figures come from the 2013 analysis.[8]Aluminium and other elements in selected herbal tea plant species and their infusions — Food Chemistry (2013) View source The urine study was small and preliminary.[9]In Vitro Digestibility of Aluminum from Hibiscus sabdariffa Hot Watery Infusion and Its Concentration in Urine — Biological Trace Element Research (2016) View source
If you are on a potassium or fluid restriction, ask your nephrologist before adding any daily tea.
A Sensible Approach
For most people with healthy kidneys, a cup or 2 of hibiscus a day is consistent with the trials. If you have stones or kidney disease, these steps keep the decision where it belongs, with your specialist.
- Healthy kidneys: stay within trial amounts.
- Uric acid stones or gout: ask first, given the 2008 finding.
- Kidney disease: ask your nephrologist, especially on dialysis.
- Hydration: hibiscus increases urine, so drink water as well.
For a fixed, countable amount, measured hibiscus capsules avoid guessing the strength of a brew.
Speak to Your Kidney Specialist Before Taking Hibiscus If
- You take blood pressure medicine or a diuretic such as hydrochlorothiazide
- You take chloroquine, simvastatin, warfarin or another medicine with a narrow margin
- You take insulin or another glucose-lowering medicine
- You are pregnant, trying to conceive or breastfeeding
- You have kidney disease, kidney stones or blood pressure that already runs low
Frequently Asked Questions
What is the best tea to drink if you have kidney problems? +
That depends on your condition and restrictions, so ask your nephrologist. Hibiscus is not an automatic choice, because its infusions carry up to 1.2 mg of aluminium per litre.
What drink is hardest on the kidneys? +
No single drink is worst for everyone. For hibiscus, the 1 harmful signal came from rats drinking a 6% infusion as their only fluid for 1 month.
Why shouldn't you drink hibiscus tea every day? +
Most adults can, within trial amounts of 2 to 3 cups. The reasons to avoid daily use are pregnancy, low blood pressure, certain medicines and kidney disease, where its aluminium and potassium matter.
Is hibiscus acidic? +
Yes. Organic acids, led by hibiscus acid, made up about 90% of the measured active compounds in a 2023 analysis of a hibiscus drink.
Does hibiscus tea cause kidney stones? +
There is no human evidence that it does. 2 small urine studies gave mixed signals, and 2 rat studies found fewer calcium oxalate crystals.
Is hibiscus tea high in oxalate? +
It was not among the high-oxalate foods named in a 2021 analysis of 109 foods, and a 2026 study found oxalate in roselle calyces below tolerable limits.
Does hibiscus tea help with uric acid? +
It raised uric acid excretion in urine in a 2008 study of 18 people, without changing blood levels over 15 days. It has not been tested for gout.
Is hibiscus tea safe with kidney disease? +
It has not been tested in advanced kidney disease. 1 trial added a 350 mg hibiscus pill to valsartan in mild disease for 90 days, under supervision. Ask your nephrologist first.
Does hibiscus tea contain potassium? +
Yes. A 2013 analysis found hibiscus infusions had the highest potassium of 6 herbal teas tested, which matters on a potassium-restricted diet.
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