Can You Take CBD with Vitamins and Supplements?

What supplements should you not take with CBD?

No regulator publishes a list of supplements to avoid with CBD. What exists is evidence about specific ingredients, mostly from prescription CBD studies and from safety reviews of the herbs themselves. These are the ones worth checking before you combine them.

How can CBD interact with a supplement?

There are three routes, and only the first is a true interaction in the pharmacology sense.

Shared liver enzymes. CBD is broken down mainly by the enzymes CYP3A4 and CYP2C19. In lab tests it also inhibits CYP1A2, CYP2C9, CYP2C19 and several others, according to the Epidyolex summary of product characteristics (opens in a new tab). In people, CBD at 750 mg twice a day raised exposure to a 200 mg dose of caffeine by 95%, which the SmPC describes as weak inhibition of CYP1A2. A supplement that speeds up those enzymes can lower CBD levels. One that relies on them can build up.

Side effects that add together. The most common side effects of prescription CBD are sleepiness, reduced appetite, diarrhoea, fever, tiredness and vomiting, and the SmPC says other sedating substances, including alcohol, can add to the sleepiness. A supplement with the same side effect doesn't need to touch CBD's metabolism to make it stronger.

Strain on the liver. CBD can cause dose-related rises in the liver enzymes ALT and AST (SmPC (opens in a new tab)), including in healthy adults in a 2025 trial run by the FDA (opens in a new tab), and our article on CBD side effects and liver findings has the figures. Adding a herb that has its own liver reports puts two unknowns in the same place.

All of this human data comes from doses of hundreds of milligrams a day or more. Prescription CBD is studied at 10 to 25 mg per kg of body weight a day, and the 2025 trial run by the FDA used about 400 mg a day. Florian et al. (2025) (opens in a new tab) note that studies under 50 mg a day have not reported these liver enzyme rises, though those studies were smaller.

Can you take CBD and melatonin together?

No study has measured what happens to melatonin levels when people take it with CBD. Three things are known.

Melatonin is broken down mainly by CYP1A enzymes, according to the EU product information for Circadin (opens in a new tab), a prescription melatonin. The same document says fluvoxamine, a medicine that blocks CYP1A2 and CYP2C19, raised melatonin exposure 17-fold, and that melatonin can add to the sedation of sleeping pills such as zolpidem. CBD inhibits both of those enzymes in lab tests.

A 2025 study by Zheng and colleagues (opens in a new tab) tested the pair in liver cells, rats and dogs. CBD slowed melatonin breakdown in human liver material and raised melatonin exposure in dogs. In rats the picture was mixed: as the CBD dose went up, melatonin peaked lower and stayed around longer, and total exposure fell to 45% at the highest dose. So the animal results point in different directions. A computer model, based on blood levels reported after 70 to 2,000 mg of CBD in people, projected an 8- to 12.5-fold rise in human melatonin exposure. The authors expect real levels to be lower, because CBD also slowed melatonin uptake from the gut in their cell tests. None of this was measured in people.

The one human trial we found that gave both is a 2023 randomised trial of 1,793 US adults (opens in a new tab) with sleep disturbance. Participants took capsules with 15 mg CBD, 5 mg melatonin, or combinations with other cannabinoids, for four weeks. About 12% reported a side effect, none severe, and rates were similar across groups. The trial wasn't designed to study interactions, side effects were self-reported online, and the products came from the manufacturer that partnered on the study.

Melatonin's legal status also varies. In Denmark the Danish Medicines Agency has classed melatonin supplements such as NOW Melatonin as medicines (opens in a new tab), and the two melatonin medicines that came onto the Danish market in 2020 (opens in a new tab) are prescription-only. In Germany it is sold both as a food supplement and as a prescription medicine (opens in a new tab). Labels aren't always accurate either: a 2023 analysis of 25 US melatonin gummies (opens in a new tab) found 74% to 347% of the stated melatonin, and five of the products also contained CBD.

If you take both and then drive, read our guide on CBD, drowsiness and driving. For what CBD studies have tested on sleep, see CBD and sleep research.

Can you take magnesium with CBD?

We found no study that tested magnesium with CBD and no documented interaction. Magnesium isn't broken down by the liver enzymes CBD affects.

The overlap to watch is the gut. EFSA's upper limit of 250 mg a day for supplemental magnesium is based on mild diarrhoea, which the Scientific Committee on Food (opens in a new tab) found in a small share of adults at about 360 mg a day. Diarrhoea is also one of the most common side effects of prescription CBD. The 250 mg limit covers magnesium from supplements, water and fortified foods, not magnesium naturally in food, so add up every product that contains it.

Can you take CBD with ashwagandha?

No study has tested the combination. The concern is ashwagandha's own safety record.

Denmark's food authority says ashwagandha is illegal to sell as food in Denmark (opens in a new tab), based on a 2020 risk assessment by the Technical University of Denmark that found effects on sex hormones and reproduction. Germany's Federal Institute for Risk Assessment (BfR) advised in September 2024 (opens in a new tab) that children, pregnant and breastfeeding women and people with liver disease should not take it. The BfR noted case reports of liver damage, including acute liver failure, and reported drowsiness among its acute effects. It said the data were too limited to set a safe intake.

Since CBD can also raise liver enzymes and cause drowsiness, the two share both concerns, even without a direct interaction.

Is it safe to take CBD with kava?

There is no study of the combination, and kava's liver record is the reason it's restricted. In 2002 the UK Committee on Safety of Medicines reviewed 68 case reports of liver toxicity linked to kava and concluded it could cause serious liver damage, according to a 2026 review paper for the UK Committee on Toxicity (opens in a new tab). Food containing kava has been banned for sale in England (opens in a new tab) since January 2003. We didn't find an EU-wide rule on kava in food, so check with your national food authority.

Which herbal supplements are known to interact with CBD?

St John's wort is the clearest example. The Epidyolex SmPC (opens in a new tab) lists it alongside rifampicin and carbamazepine as a strong inducer of CYP3A4 and CYP2C19. Rifampicin cut blood levels of CBD by about 30% and of its active breakdown product by about 60%, and the SmPC says St John's wort may have a similar effect. The St John's wort pairing itself hasn't been tested.

For most other herbs, there's no CBD-specific data. The useful question for each one is whether its own safety information mentions liver enzymes, the liver itself, or drowsiness. If it does, ask a pharmacist before you add CBD.

Can I take CBD with fish oil or omega-3?

We found no study of CBD with fish oil. Fish oil's own interaction warnings concern bleeding with blood thinners. The US Office of Dietary Supplements says fish oil might prolong clotting times with warfarin (opens in a new tab), although most research at 3 to 6 g a day found no significant effect. EFSA considers combined EPA and DHA intakes of up to about 5 g a day safe in the long term, according to the same fact sheet.

That matters for CBD because warfarin is also one of the medicines CBD is documented to affect. If you take a blood thinner, the question is the medicine, and our drug interactions guide covers it. For how omega-3 and curcumin sit alongside CBD in a single capsule, see what is in a multi-ingredient CBD capsule.

Can you take CBD with vitamins or a multivitamin?

No interaction between CBD and vitamins has been reported in the sources we checked. The practical risk is taking too much of a vitamin because it's in two or three products: a multivitamin, a vitamin D drop, and a CBD capsule with added vitamins.

EFSA sets a tolerable upper intake level (UL) for many nutrients: the most you can take every day, from all sources, without expected harm. These are the adult figures for nutrients that often appear in more than one product.

Except for magnesium, the limits cover food as well as supplements, so your diet counts too. EFSA says Europeans are unlikely to exceed the vitamin D limit unless they regularly take high-dose supplements. For more on that pairing, read CBD and vitamin D.

How to check your supplement stack

Write everything down in one place before you add CBD. A table like this is enough, and it's what a pharmacist will want to see.

Then go through it:

1. Add up each vitamin and mineral across all products and compare the total with the EFSA limits above.
2. Mark any herb whose safety information mentions the liver, liver enzymes or drowsiness.
3. Mark anything that also makes you sleepy, including melatonin and alcohol.
4. List every prescription and over-the-counter medicine on the same sheet.
5. Show the sheet to a pharmacist or doctor, especially if anything is marked.

If you don't know why you take a product, that's worth raising too. Dropping one supplement makes the rest easier to review.

Who should get advice before combining CBD with supplements?

Regulators already name groups for whom CBD itself isn't recommended or whose safety can't be established:

• EFSA (EU): people under 25, pregnant and breastfeeding women, and people on medication (February 2026 (opens in a new tab)).
• FSA (UK): children, people taking any medication, people trying to conceive, and pregnant or breastfeeding women, unless under medical direction (FSA advice (opens in a new tab)).

People with liver disease have extra reason to ask first, given the liver warnings for CBD, ashwagandha and kava above.

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