Last updated: October 2026
At high doses, CBD can raise liver enzymes in some people. In a 2025 FDA trial, 5.6% of healthy adults taking about 350mg a day had raised liver enzymes within four weeks, against none on placebo. There’s little evidence of harm at the much lower doses in food supplements, but research is limited, so dose matters.
Below: what the trials found, what dose is involved, who should be careful, warning signs, and how to use CBD sensibly.
What the research found
| Study | Dose | What it found |
|---|---|---|
| FDA trial, 2025 (201 healthy adults) | 5mg per kg a day (about 350mg for a 70kg adult) for 28 days | 8 people (5.6%) on CBD had liver enzymes over 3 times the normal limit; none on placebo |
| Phase 1 trial, 2021 (16 healthy adults) | 1,500mg a day | 7 had raised liver enzymes, 5 of them more than 5 times the normal limit, within 2 to 4 weeks |
| Epidyolex (prescription CBD) | 10 to 25mg per kg a day | Raised liver enzymes are a known side effect, more likely alongside the epilepsy medicine valproate; liver blood tests are required during treatment |
| Mouse study, 2019 | Up to 2,460mg per kg | Liver damage at very high doses. This is the study behind many alarming headlines |
All of these used doses far higher than a typical food supplement. They show the liver is the main thing to watch with CBD, which is why the UK’s food safety advisers based their advice on it.
Why dose matters
The FSA’s scientific advisers found signs of liver effects in people from about 5mg per kg a day, or roughly 350mg for a 70kg adult. They set 10mg a day as a precautionary level that protects against the most sensitive known effects on the liver and thyroid, allowing a large safety margin because long-term data is missing.
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.
For how much is in each drop of our oils, see how much CBD to take.
What raised liver enzymes mean
ALT and AST are enzymes measured in a liver function blood test. A rise means liver cells are under strain, but it doesn’t always mean lasting damage, and enzymes can also rise after hard exercise, alcohol or some medicines. In the trials, people with large rises stopped taking CBD. If you’re having a blood test, tell your doctor you take CBD.
Who should be careful
- People with liver disease or raised liver enzymes: speak to your GP before using CBD.
- People taking medicines, especially valproate, other epilepsy medicines, statins, blood thinners, or anything with a liver warning. See CBD and medication.
- Regular heavy drinkers. See CBD and alcohol.
- Anyone taking high doses of CBD for long periods.
- Pregnancy and breastfeeding: we don’t recommend our products during pregnancy or breastfeeding.
Signs of a liver problem
Stop taking CBD and see your GP if you notice:
- yellowing of the skin or the whites of the eyes
- dark urine or pale stools
- itchy skin
- pain in the upper right of your tummy
- unusual tiredness, feeling sick or loss of appetite
Yellow skin or eyes need urgent medical advice. Call NHS 111 or your GP the same day.
How to use CBD sensibly
- Start low and increase slowly, only if you need to.
- Choose a lab-tested product so you know the real dose. Ours are available on request: see our lab testing page.
- Avoid stacking several CBD products at once without adding up the total.
- Check your medicines with a pharmacist first.
For other effects to know about, see CBD side effects.
FAQs
Is CBD bad for your liver?
At high doses it can raise liver enzymes in some people. There’s little evidence of harm at typical supplement doses, but long-term research is limited.
How much CBD affects the liver?
Liver effects have been seen in people from about 5mg per kg a day, roughly 350mg for a 70kg adult. The FSA advises 10mg a day as a precaution.
Can CBD cause liver damage?
Very high doses have caused raised liver enzymes in trials and liver damage in mice. Lasting liver damage from supplement doses hasn’t been shown.
Will CBD show up on a liver function test?
CBD itself isn’t measured, but at high doses it can raise ALT and AST. Tell your doctor you take CBD before a blood test.
Can I take CBD if I have fatty liver?
Speak to your GP first. Anyone with a liver condition should get medical advice before taking CBD.
Is it safe to take CBD every day?
Many adults do. Keep to a sensible dose, increase slowly, and check with your GP or pharmacist first if you take any medication.
Sources
- Florian J et al. Cannabidiol and liver enzyme level elevations in healthy adults: a randomized clinical trial. JAMA Intern Med, 2025.
- Watkins PB et al. Cannabidiol and abnormal liver chemistries in healthy adults: results of a phase I clinical trial. Clin Pharmacol Ther, 2021.
- Ewing LE et al. Hepatotoxicity of a cannabidiol-rich cannabis extract in the mouse model. Molecules, 2019.
- ACNFP and COT. Provisional CBD acceptable daily intake, 2023.
- NHS. Liver disease.
