Herbs and Kidney Disease: Potassium, Oxalate, Aristolochic Acid and Other Cautions

If you have kidney disease, are on dialysis or have had a kidney transplant, ask your kidney doctor (nephrologist) or kidney pharmacist before using any herbal product. The National Kidney Foundation (US) says herbal supplements can make kidney disease worse, interact with prescription medicines or raise the risk of chronic kidney disease (CKD) complications, and that for transplant recipients interactions can increase the risk of losing the new kidney. [1] Do not stop a prescribed medicine on your own; ask the prescriber or pharmacist.

Aristolochic acid: the best-documented kidney toxin

Aristolochic acids are found naturally in many plants of the genus Aristolochia (birthworts or pipevines) and some Asarum plants (wild ginger), according to the National Cancer Institute. [2] Some herbal products containing them are marketed as dietary supplements or traditional medicines. [2] The NCI says cancers of the upper urinary tract and bladder have been reported among people whose kidneys were damaged by herbal products containing aristolochic acids, and advises: do not use herbal products that contain aristolochic acids. [2]

A 2023 review of aristolochic acid nephropathy reports that it is a rapidly progressive kidney scarring (interstitial fibrosis) caused by exposure, that cases are still sporadically reported although regulation has made them decline sharply, and that there is no effective treatment for delaying or reversing the kidney deterioration. [3] The review also says the true number of cases and exposures is unknown and might be largely underestimated. [3] The National Kidney Foundation notes aristolochic acid is banned in many countries but still present in some traditional remedies. [1] More detail: Aristolochic acid and herbal nephropathy. See adulteration and substitution of herbs.

Potassium

The NIDDK says CKD can make it harder for the kidneys to remove potassium, and that blood potassium can become very high; too much or too little potassium can cause heart and muscle problems. [4] NKF lists herbal supplements that can have high potassium content, including noni, stinging nettle leaf, dandelion, bitter melon, kelp, garlic leaf and turmeric rhizome, and says labels promoting "electrolyte support" or "superfood green powders" may signal high potassium. [1] Memorial Sloan Kettering lists case reports of kidney failure and dangerously high potassium after noni juice use. [5] See noni.

Licorice is a different potassium and blood pressure issue. NCCIH says that even small amounts of glycyrrhizin from licorice root products have been linked to severe adverse effects in people with hypertension and in people with heart or kidney conditions. [6]

Phosphorus and oxalate

NKF also lists herbal supplements it says can be high in phosphorus (for example alfalfa, spirulina and chlorella, milk thistle seed, flaxseed, and turmeric rhizome), with seaweed, green powders and seed products most likely. [1] Oxalate: "Proper evidence not found". The kidney sources read for this page (NKF, NIDDK, NCI, a 2023 review) do not discuss herbs and oxalate, so this page makes no claim about oxalate or kidney stones.

"Kidney detox" and cleanse products

NKF advises avoiding teas and supplements marketed as a "kidney detox" or "kidney cleanse", saying evidence is limited and some ingredients can interact with medicines or damage the kidneys. [1] It also advises avoiding combination products and "proprietary blends" because amounts of each ingredient are not known, and notes some supplements contain ingredients not printed on the label, including prescription medicines. [1]

Contamination and quality

NKF says herbal supplements can contain contaminants such as heavy metals (lead, mercury or arsenic), and that quality and potency vary between batches. [1] See product quality and contamination and quality testing and certifications.