CBD
A hemp compound sold as a supplement, taken for anxiety, pain or sleep.
- Anxiety and stress
- Pain and aches
- Sleep
A plain-English overview, not advice. Written from published reviews and trials and from what people say in public forums.
On this page
What is CBD?
Cannabidiol, usually shortened to CBD, is one of the natural compounds found in the Cannabis sativa plant, typically extracted from hemp varieties bred to be very low in the plant’s intoxicating compound, THC. In the UK it is sold as a food supplement - oil drops, capsules or gummies - entirely separate from the much higher-strength, prescription-only cannabis-based medicines used for a small number of named conditions. It has become widely available on general retailer shelves over the past decade, and people buy it above all for anxiety, pain and sleep.
Why do people take CBD?
Anxiety and stress
The thinking. Anxiety and a wish to feel calmer are among the most common reasons people buy CBD, whether as a daily habit or before something they expect to find stressful. Because it does not produce the intoxicating effects of cannabis’s better-known compound, THC, it is taken with the idea that it might settle nerves without a noticeable high.
What research has found. Two trials tested this directly. One gave college students a single dose before a stressful exam and found no effect on anxiety at any of the doses tried. The other compared a lower, commercially typical dose against a higher research dose over two weeks in adults who described themselves as frequent worriers: the worry itself did not ease at either dose, though the higher dose left people reporting fewer physical symptoms of anxiety than a placebo did. Studies here point in different directions, so this one is still being worked out; the dose, how long people took it and who took part all seem to matter.
Pain and aches
The thinking. Pain and everyday aches are another common reason people buy CBD, often tried alongside whatever they are already taking for it, from a strained back to arthritic joints.
What research has found. One trial tested this directly, giving a single dose to a hundred people arriving at an emergency department with sudden low back pain, on top of their usual pain relief. Their pain scores two hours later were much the same whether they had taken CBD or a placebo. Few studies have measured this yet, so there is little to go on either way.
Sleep
The thinking. Sleep is one of the most common reasons people buy CBD, usually taken in the evening in the hope of settling down more easily or sleeping more soundly through the night.
What research has found. Two trials tested this: one in adults with ongoing insomnia taking a moderate nightly dose, and one in healthy young adults taking a lower daily dose for eight weeks. Neither found a change in how long people took to fall asleep, but the insomnia trial found people slept more efficiently and reported feeling better in themselves by the second week, and the other found people rated their sleep quality as improved on a questionnaire even though the total time they spent asleep was unchanged. The studies disagree, so this is unsettled: dose, duration and who took part all seem to shift the result.
What does CBD do in the body?
CBD, or cannabidiol, is one of more than a hundred compounds found in the cannabis plant. Unlike the plant’s better-known compound, THC, it is not intoxicating. Most of what is known about how it acts in the body comes from research into its use in epilepsy, where the exact way it reduces seizure activity is still described as unclear, though researchers have proposed it may act on several nerve-cell receptors and channels.
Once swallowed, only a small proportion of a dose reaches the bloodstream: much of it is broken down by the liver before it gets there. Taking it with a fatty meal increases the amount absorbed by roughly fourfold. This uneven, variable absorption is one of the reasons researchers give for why blood levels, and any effects, differ so much from one study, and one person, to the next.
What do people say about taking CBD?
These are anecdotes people have shared, not evidence.
What people like
- All six threads read were from Mumsnet, so the pattern below may say as much about that community as about CBD itself.
- Often, people describe sleeping better after taking it nightly for some weeks, several mentioning longer or steadier sleep than before.
- Several describe feeling calmer or better able to switch off in the evening, without feeling intoxicated or knocked out.
- A few describe marked relief from joint or arthritic pain, one calling the change dramatic; another mentions taking it alongside prescribed painkillers that were not fully working.
Common complaints
- Often, people report no noticeable effect at all, including some who had tried it for anxiety, joint pain or general aches.
- Several question whether any effect is more than a placebo, and a few say plainly they think it is overpriced.
- A minority raise quality concerns, saying some products seem to contain less CBD than advertised, and that it takes trial and error to find one that suits them.
- A few mention vivid dreams, an unpleasant taste, nausea at higher strengths, or stomach upset that eased after switching to a different oil base.
How people take it
- People describe taking drops under the tongue, most starting with a low strength and increasing gradually; daily amounts mentioned in one thread ranged from about 5 mg up to 20 mg or more.
- Several say it took weeks or months of regular use before they noticed any change, rather than a single dose making a difference.
- A few mention taking it alongside other things tried for the same reason, among them prescribed painkillers or other supplements.
- A minority raised questions about how it might sit alongside other medicines they were already taking, without a settled answer appearing in the discussion.
Read from these public discussions:
- Canabis Oil - CBD (Mumsnet, 2018)
- CBD oil (Mumsnet, 2019)
- CBD oil for anxiety - has anyone tried? (Mumsnet, 2019)
- To ask if you have tried CBD oil for arthritis pain? (Mumsnet, 2019)
- CBD oil for sleep (Mumsnet, 2024)
- Is CBD oil worth trying for anxiety, or a waste of money? (Mumsnet, 2026)
What forms of CBD are there?
| Form | What’s different | Per serving, on products we list |
|---|---|---|
| CBD oil | Liquid drops measured with a dropper; CBD isolate alone, or a broad- or full-spectrum extract with other plant compounds. | not in our price tables yet |
| CBD capsules | CBD, often as an oil blend, enclosed in a swallowed capsule, softgel or tablet. | not in our price tables yet |
| CBD gummies | CBD mixed into a chewable sweet such as a gummy or pastille, each stating its amount per piece. | not in our price tables yet |
What else is worth knowing about CBD?
- A review of CBD’s drug interactions reported that it has been found to interact with several types of medicine, including anti-epileptic drugs, antidepressants, opioid painkillers and paracetamol, as well as with alcohol.
- Trials in people taking it for epilepsy and psychiatric conditions, at doses far higher than a food-supplement label states, reported drowsiness, diarrhoea, fatigue, vomiting and raised liver-enzyme readings, some of this tied to other medicines being taken at the same time.
- A review of studies using up to 400 mg of CBD a day reported clearer results from around 300 mg a day upwards, and more marginal, less consistent results below that.
- How much of a dose reaches the bloodstream depends heavily on whether it is taken with food: one estimate put oral bioavailability at around 6% on an empty stomach, rising roughly fourfold with a high-fat meal.
- Most research so far suggests CBD is not converted into psychoactive THC inside the body, though it can degrade into psychoactive compounds if stored in acidic conditions, and researchers say the storage stability of commercial products needs more attention.
If you take medication, are pregnant, or have a health condition, check with a pharmacist or GP first.
The research behind this page (11 studies)
- A Double-Blind, Randomized, Placebo-Controlled Test of the Effects of Cannabidiol on Experiences of Test Anxiety Among College Students. (2023, randomised trial)
- The effects of cannabidiol on worry and anxiety among high trait worriers: a double-blind, randomized placebo controlled trial. (2023, randomised trial)
- The CANBACK trial: a randomised, controlled clinical trial of oral cannabidiol for people presenting to the emergency department with acute low back pain. (2021, randomised trial)
- Cannabidiol for moderate-severe insomnia: a randomized controlled pilot trial of 150 mg of nightly dosing. (2024, randomised trial)
- Eight Weeks of Daily Cannabidiol Supplementation Improves Sleep Quality and Immune Cell Cytotoxicity. (2023, randomised trial)
- Cannabidiol Adverse Effects and Toxicity. (2019, review)
- Critical Aspects Affecting Cannabidiol Oral Bioavailability and Metabolic Elimination, and Related Clinical Implications. (2020, review)
- The safety and efficacy of low oral doses of cannabidiol: An evaluation of the evidence. (2023, review)
- Pharmacological and Therapeutic Properties of Cannabidiol for Epilepsy. (2019, review)
- Cannabidiol Interactions with Medications, Illicit Substances, and Alcohol: a Comprehensive Review. (2021, review)
- Conversion of Cannabidiol (CBD) into Psychotropic Cannabinoids Including Tetrahydrocannabinol (THC): A Controversy in the Scientific Literature. (2020, review)
How much does CBD cost?
That depends on the form and the pack, so we work out the price of the same dose of every CBD product we can find and rank them.