"Natural" does not mean "safe for your kidneys". A surprising number of herbal supplements sold in the UK have been linked to kidney damage. This article rounds up the ones the NHS, the MHRA and Kidney Care UK specifically warn about.
Herbs to avoid in CKD
- Aristolochia (birthwort) — banned in the UK because of clear evidence of kidney failure and urinary tract cancer.
- Liquorice root in large amounts — can cause high blood pressure and low potassium.
- St John's Wort — interacts with ciclosporin, tacrolimus and other transplant medicines.
- Cat's claw, juniper, parsley root in concentrated form — case reports of acute kidney injury.
- High-dose creatine — usually safe in healthy adults, but not recommended in CKD.
- Bodybuilding "kidney detox" or "cleanse" products — often contain unlisted ingredients flagged by the MHRA.
Supplements that interact with kidney medication
Even widely sold supplements can be a problem. Vitamin K can affect warfarin dosing. Magnesium-based laxatives can build up in CKD. Iron supplements should usually be timed away from phosphate binders. Always tell your GP, renal pharmacist or dietitian about every product you take.
Buying safely in the UK
- Look for the THR (Traditional Herbal Registration) mark — it shows the product has been registered with the MHRA.
- Avoid products bought from unregulated overseas websites.
- Yellow Card any suspected side effects to the MHRA.
Bottom line
If you have CKD, treat any herbal supplement the way you would a prescription medicine — check with a UK-registered pharmacist before starting it.