Last updated: October 2026
There’s no evidence that CBD harms healthy kidneys. CBD is broken down mainly by the liver, and a 2020 study found kidney impairment, even severe, didn’t change how the body handled a 200mg dose. The real kidney concerns are medicine interactions, especially transplant drugs like tacrolimus, and poor-quality products. People with kidney disease should check with their kidney team first.
Below: how CBD is processed, what the research shows, kidney disease and transplants, kidney stones, and how to use CBD safely.
How the body processes CBD
After you take CBD, the liver breaks most of it down. Its by-products leave the body mainly in faeces, with a smaller share in urine. This is different from medicines that are cleared mainly by the kidneys, which often need lower doses in kidney disease. See how long CBD stays in your system.
Is CBD bad for your kidneys? The research
| Source | What it found |
|---|---|
| Kidney impairment study, 2020 (people with mild to severe kidney impairment) | No meaningful difference in CBD levels compared with people with normal kidneys after a 200mg dose; well tolerated |
| Kidney specialists’ review, 2020 | Cannabis doesn’t seem to affect kidney function in healthy people; CBD may raise tacrolimus levels; little evidence exists for people with kidney disease |
| Prescription CBD (Epidyolex) trials | Kidney problems weren’t among the main side effects, even at very high doses |
High doses of CBD are more associated with liver effects than kidney effects. See is CBD bad for your liver? and CBD side effects.
CBD and kidney disease
If you have chronic kidney disease, you’re likely to be taking several medicines, and some are processed by the same liver enzymes as CBD. There’s also very little research in people with kidney disease. So:
- Speak to your kidney team or GP first.
- Start with a low dose if they agree, and tell them at your next blood test.
- Avoid products with added minerals or unlisted ingredients, as some, such as potassium, can be a problem in kidney disease.
- Magnesium supplements: don’t take them without medical advice, as magnesium can build up when kidneys don’t work well.
Kidney transplants and tacrolimus
This is the most important kidney-related warning. A 2019 case report found CBD, at very high trial doses, roughly tripled blood levels of tacrolimus, an anti-rejection medicine, and kidney specialists have flagged the same risk. Tacrolimus levels that are too high can damage the kidneys. If you’ve had a transplant, don’t take CBD unless your transplant team agrees and monitors your levels. See CBD and medication.
CBD and kidney stones
iThere’s no evidence that CBD causes or treats kidney stones. Staying well hydrated is the main thing that helps prevent them. If you get stones, check any supplement with your GP, as some herbal products, such as chaga mushroom, are very high in oxalates.
How to use CBD safely
- Choose a lab-tested product so you know what’s in it, including that it’s free from heavy metals. See how to read a CBD lab report.
- Start low, increase slowly. See how much CBD to take.
- Check every medicine with a pharmacist.
The FSA’s 10mg a day figure is precautionary advice rather than a legal limit, set while longer-term safety research continues. At Evopure we think it is a very cautious figure, and many adults use more. If you go above it, increase slowly, and check with your GP or pharmacist first if you take any medication.
All our CBD oils and capsules are broad spectrum and batch tested by an independent lab, with reports available on request from our lab testing page. We don’t recommend our products during pregnancy or breastfeeding.
iGout and kidney problems often go together; see CBD oil for gout for what to check with your pharmacist.
Our chaga and kidneys guide sets out the case reports and who should avoid it.
Sources 4
- Tayo B et al. Pharmacokinetics, safety and tolerability of cannabidiol in subjects with mild to severe renal impairment. Clin Pharmacokinet, 2020.
- Rein JL. The nephrologist’s guide to cannabis and cannabinoids. Curr Opin Nephrol Hypertens, 2020.
- Leino AD et al. Evidence of a clinically significant drug-drug interaction between cannabidiol and tacrolimus. Am J Transplant, 2019.
- NHS. Chronic kidney disease.
