The gap between what CBD can do and what it is sold for is wide. The strong evidence is narrow and specific: a purified prescription cannabidiol, Epidiolex, cuts seizures in three rare epilepsies in randomized trials, and single doses lower acute anxiety in experimental settings at one particular dose. The popular case, that an over-the-counter hemp CBD oil reliably fixes chronic pain and sleep, runs far ahead of the data, which is mixed and thin.
Three consumer-market problems sit on top of that, and each is worth checking before you spend: labels that do not match the bottle, occasional THC, and a liver-enzyme and drug-interaction signal that runs through both forms. Here is where each claim actually stands.
Findings & Outcomes
What It Is
CBD, or cannabidiol, is one of the two main compounds in the cannabis plant. Unlike THC, the other one, it does not make you high. It comes in two forms that get discussed as if they were the same product:
- Prescription cannabidiol (Epidiolex) is a purified pharmaceutical liquid approved for specific rare epilepsies, made to a known strength and tested in randomized trials.
- Over-the-counter hemp CBD is the oils, gummies, capsules, and creams sold as supplements. It is held to no such manufacturing standard, and it carries almost none of the trial evidence people assume it does.
Almost all of the seizure trials, the anxiety experiments, and the liver-enzyme findings used the purified form at a controlled dose, often far higher than a supplement delivers. A strong result for Epidiolex does not transfer to a retail gummy of uncertain content.
What It Does
CBD's uses fall along a steep gradient of evidence, and the cards below are ordered by it. At the strong end sit three rare epilepsies, where a purified prescription form reduced seizures in randomized trials. These results are why cannabidiol became a medicine at all, and they are as solid as evidence on this page gets. In Dravet syndrome, a trial of 120 children cut monthly convulsive seizures by about 39% against about 13% on placebo; in Lennox-Gastaut syndrome, two trials reduced drop seizures by roughly 42 to 44% against 17 to 22%; in tuberous sclerosis complex, a trial of 224 patients cut seizures by about 48% against about 27%. The results are narrow by design: specific rare epilepsies, at a controlled dose, not a general claim that CBD calms the brain.
Below that is acute, situational anxiety, resting on a thinner kind of evidence. Small experiments gave people a single dose before a simulated public-speaking test. A 300 mg dose lowered the anxiety spike, while 150 mg and 600 mg did not, an inverted-U pattern where the dose matters and more is not better. This says nothing yet about a daily CBD gummy treating an anxiety disorder over months, which has barely been tested.
At the weak end are the two uses CBD is sold for most, chronic pain and sleep. The best current systematic review of cannabis-based products found the pain evidence limited, with any benefit small, and the data on CBD alone thinner still. For sleep, most of what exists is uncontrolled case reports and studies where sleep improved as a knock-on from reduced anxiety. That gap is a fact about the research: Western trials have not shown a reliable effect for either use, and the confident marketing has outrun them.
The Research & Studies
Everything here is based on the research we have collected and checked, sorted into groups and ordered with the strongest evidence first. Click any claim to open the studies behind it.
Seizure Control
Purified CBD cut monthly convulsive seizures about 39% in Dravet syndrome, versus 13% on placebo
In a rigorous trial of children with a severe form of epilepsy, a purified prescription form of CBD cut convulsive seizures by roughly 39%, while placebo cut them by about 13%. This is the strongest and best-established use of cannabidiol.
This double-blind placebo-controlled randomized trial added cannabidiol oral solution (20 mg/kg/day) or placebo to standard antiepileptic treatment. Beyond seizure counts, more participants on cannabidiol were rated improved on a global impression scale. Adverse effects were more common on cannabidiol and included somnolence, diarrhea and raised liver aminotransferases, the last more frequent in those also taking valproate. The result was replicated and underpins the drug's regulatory approval for Dravet syndrome.
Who this may not transfer to:Dravet syndrome affects both sexes and the trial enrolled both; the anticonvulsant effect is not sex-specific.
This is a prescription medicine used under a neurologist for a specific rare epilepsy, with liver monitoring and attention to drug interactions, not a reason to expect a retail CBD product to control seizures. The dose is high and the population narrow.
The study · 1
Devinsky et al., Trial of Cannabidiol for Drug-Resistant Seizures in the Dravet Syndrome · N Engl J Med 2017;376(21):2011-2020
Prescription CBD cut drop seizures 42 to 44% in Lennox-Gastaut syndrome, versus 17 to 22% on placebo
In two solid trials of another rare childhood epilepsy, prescription CBD roughly halved the drop-type seizures for many patients, clearly more than placebo. This is the second well-established seizure use.
Both trials added cannabidiol oral solution to existing antiepileptic drugs in patients with Lennox-Gastaut syndrome. The 10 mg/kg dose in the Devinsky trial worked nearly as well as 20 mg/kg with fewer side effects, suggesting a lower dose can suffice. As in Dravet syndrome, somnolence, decreased appetite, diarrhea and raised liver enzymes were the notable adverse effects, and liver-enzyme elevations were more common with concomitant valproate.
Who this may not transfer to:Both trials enrolled both sexes and the anticonvulsant effect is not sex-specific.
Like the Dravet result, this is a prescription use under specialist care with monitoring, and the lower 10 mg/kg dose is often preferred. It is not evidence for retail CBD in ordinary seizure disorders.
The studies · 2
Devinsky et al., Effect of Cannabidiol on Drop Seizures in the Lennox-Gastaut Syndrome · N Engl J Med 2018;378(20):1888-1897
Thiele et al., Cannabidiol in patients with seizures associated with Lennox-Gastaut syndrome (GWPCARE4) · Lancet 2018;391(10125):1085-1096
Prescription CBD cut TSC-associated seizures about 48%, versus 27% on placebo
In a third rare epilepsy, tuberous sclerosis complex, prescription CBD cut seizures by about 48% against about 27% on placebo in a solid trial. It is the third well-established seizure use, alongside Dravet and Lennox-Gastaut syndromes.
The GWPCARE6 trial added cannabidiol oral solution at 25 or 50 mg/kg/day or placebo to existing antiepileptic drugs in patients aged 1 to 65 with TSC. Both cannabidiol doses reduced seizures significantly more than placebo, with the lower 25 mg/kg/day dose preferred for its better tolerability. The most common adverse effects were diarrhoea and somnolence, more frequent at the higher dose, and elevated liver transaminases occurred in about one in five on cannabidiol and none on placebo. The result supported approval of cannabidiol for TSC-associated seizures.
Who this may not transfer to:The trial enrolled both sexes (about 42% female) and the anticonvulsant effect is not sex-specific.
As with the Dravet and Lennox-Gastaut results, this is a prescription use under specialist care with liver monitoring, and the lower 25 mg/kg/day dose is generally preferred. It is not evidence for retail CBD in ordinary seizure disorders.
The study · 1
Thiele et al., Add-on Cannabidiol Treatment for Drug-Resistant Seizures in Tuberous Sclerosis Complex: A Placebo-Controlled Randomized Clinical Trial (GWPCARE6) · JAMA Neurol 2021;78(3):285-292
Anxiety And Stress
A single 300 mg dose of CBD lowered anxiety before a public-speaking test, while 150 and 600 mg did not
Taking a single moderate dose of CBD before a stressful public-speaking task lowered anxiety in small trials, with around 300 mg working better than higher or lower doses. It is an early, short-term finding about situational anxiety.
Bergamaschi 2011 gave 24 treatment-naive social anxiety patients 600 mg of cannabidiol or placebo before a simulated public-speaking test and found reduced anxiety, cognitive impairment and discomfort on the active drug. Linares 2019 tested 150, 300 and 600 mg against placebo in 57 healthy men and found only 300 mg significantly reduced anxiety, describing an inverted-U dose-response. These are single-dose, short-term experiments in specific settings, not trials of daily use for an anxiety disorder.
Who this may not transfer to:The primary social-anxiety trial enrolled both sexes; the confirmatory dose-response study was in men only, so the exact optimal dose in women is less certain.
The evidence supports a single moderate dose before a specific stressor rather than a large daily dose, since more did not help. It should sit alongside established treatment for an anxiety disorder rather than replace it, and drug interactions should be checked first.
The studies · 2
Bergamaschi et al., Cannabidiol reduces the anxiety induced by simulated public speaking in treatment-naive social phobia patients · Neuropsychopharmacology 2011;36(6):1219-1226
Linares et al., Cannabidiol presents an inverted U-shaped dose-response curve in a simulated public speaking test · Braz J Psychiatry 2019;41(1):9-14
Pain
CBD on its own did not clearly relieve chronic pain beyond placebo
Despite heavy marketing of CBD for pain, the best current review finds the evidence weak, with any benefit small, and the data on CBD by itself too thin to conclude it reliably relieves chronic pain.
The review synthesized randomized trials and observational studies of cannabis-based products for chronic pain. Products high in THC showed at most small short-term benefits with meaningful side effects, and the subset of evidence on cannabidiol-only products was sparse, of low certainty, and did not establish a clear analgesic effect. Much of the popular case for CBD in pain rests on preclinical work and testimonials rather than controlled human outcomes.
Who this may not transfer to:Pooled across mixed-sex chronic-pain populations; CBD-specific subgroups were too small to assess sex differences.
A reader should treat CBD-for-pain claims with caution: the shelf implies reliable relief that the controlled evidence does not support. This is a place where the popular version runs well ahead of the research.
The study · 1
Chou et al., Cannabis-Based Products for Chronic Pain: An Updated Systematic Review · Ann Intern Med 2026;179(2):230-241
Sleep
Sleep scores improved for about two-thirds of adults on CBD in an uncontrolled clinic series
The main clinical report on CBD and sleep saw sleep scores improve for about two-thirds of people at first, but with no comparison group and gains that came and went. It is too thin to call CBD an established sleep aid.
Shannon 2019 reviewed charts from a psychiatric clinic where 72 adults received CBD (about 25 to 175 mg/day) alongside usual care, mostly for anxiety or poor sleep. Anxiety scores fell and stayed lower in most patients; sleep scores improved initially in about two-thirds but were more variable month to month. As an open, uncontrolled case series it cannot separate a true CBD effect from placebo, regression to the mean, or the knock-on effect of lower anxiety.
Who this may not transfer to:Both sexes were included in this uncontrolled clinic series; no sex-specific analysis was possible.
The durable, free groundwork for sleep does more for most people than a supplement, and CBD-for-sleep should be seen as unproven. If tried, it belongs after the basics and after checking drug interactions.
The study · 1
Shannon et al., Cannabidiol in Anxiety and Sleep: A Large Case Series · Perm J 2019;23:18-041
How It Works
Cannabidiol acts in the brain and in the liver. How far each action carries into an effect you would notice is what separates the strong uses from the marketed ones: in epilepsy the mechanism reaches a measured clinical result, in anxiety it reaches a measured lab effect at a single dose, and in chronic pain and sleep the chain from mechanism to outcome is where the case thins.
Anatomy of the Practice
1In the brain, in epilepsy
Cannabidiol changes how certain neurons fire, partly through targets other than the usual cannabis receptor, and in three rare epilepsies this translates into measurably fewer seizures in controlled trials. This is the one place the mechanism reaches a hard clinical result.
2In the stress and fear circuits
At a single dose, cannabidiol dampens activity in brain regions tied to the acute anxiety response, which fits the short-term finding that it blunts the spike of anxiety before a stressful event. The effect follows an inverted-U dose curve, so a moderate dose does more than a large one.
3In the liver
Cannabidiol is broken down by, and also inhibits, several liver enzymes in the CYP450 family. That is the root of two safety issues at once: it can raise liver-enzyme readings, and it can change the blood levels of other drugs cleared by the same enzymes.
Using CBD Well
CBD costs money, so the fair first step is to check whether the evidence supports it for your goal before spending, and then to sort out the two things that vary most between products: how much CBD is actually in the bottle, and how it acts on the medicines you already take.
Before starting CBD at any meaningful dose, list your medications and check them with a pharmacist. Cannabidiol clears through the same liver enzymes as many common drugs, and that is the caution to take most seriously.
Ways to Do It
Match the goal to the evidence first, sort out your medications, then treat product quality as the main filter in an unregulated market. Retail products rarely deliver the doses the trials used, and the label may not match the bottle.
The strong evidence is for three rare epilepsies, which are a medical route, and there is early evidence for acute, situational anxiety. For chronic pain and sleep the case is weak, so the free groundwork on the anxiety and insomnia guides is the fairer place to start than a supplement.
Cannabidiol acts on the CYP450 liver enzymes that also clear many common drugs, so before starting anything, list what you take and check it with a pharmacist or clinician. This is free, it takes one conversation, and it heads off the interactions in the cautions below.
Because labels often miss the real content, buy only products that publish a recent third-party lab test, a Certificate of Analysis, showing the actual CBD amount and confirming THC is within legal limits. No certificate, no purchase. This is the most useful quality filter in an unregulated market.
Isolate is CBD alone. Broad-spectrum adds other hemp compounds but aims to remove THC. Full-spectrum keeps a trace of THC, which is legal below a limit but can matter for drug testing and sensitivity. For anyone who must avoid THC entirely, isolate or a THC-free broad-spectrum with a Certificate of Analysis is the safer pick.
The epilepsy trials used 10 to 20 mg per kilogram of body weight a day, hundreds of milligrams for a child, and the anxiety experiments used a single 300 mg dose. A typical gummy delivers 10 to 25 mg. So even a labeled retail dose is a fraction of what the strong evidence studied, which is another reason the trial results do not transfer to the shelf.
The experimental anxiety evidence sits with a single oral dose in the region of 300 mg before a specific stressor, since higher amounts did no better. Treat this as short-term and early, keep it alongside proper care for an anxiety disorder, and re-check interactions first.
The strong seizure evidence is for a prescription product used under a neurologist for Dravet syndrome, Lennox-Gastaut syndrome or tuberous sclerosis complex, with liver-enzyme monitoring and dose adjustment of interacting drugs built in. This is a medical decision, a different thing entirely from a retail CBD oil.
Go Deeper
- Anxiety: where the early single-dose CBD evidence sits among approaches with a longer track record, and what to build first for an anxiety disorder.
- Insomnia: the durable, free groundwork for sleep, which the thin CBD-for-sleep evidence does not replace.
- Low back pain: a common reason people reach for CBD, and where the controlled pain evidence actually points.
- Interaction checker: check CBD and other supplements against the medicines you take, since the CYP450 interactions are the main thing to weigh before starting.
The Chinese Medicine View
Chinese medicine has no concept of CBD, and it would be an invention to claim otherwise. The isolated compound does not map onto the tradition. What the tradition does have is a long relationship with the cannabis plant, and that relationship is more cautious than the modern wellness framing.
The seed, Huo Ma Ren, fire hemp seed, is a recognized herb: sweet and neutral, it moistens the intestines and is used gently for dry constipation in the depleted or the elderly. That is the seed, used as a mild food-like laxative, and it is a different substance from a concentrated cannabinoid extract. It is not CBD, and pointing to it does not lend CBD a tradition it lacks. The flowering and resinous parts of the plant were known too, and classical sources treat them warily, noting that in excess they can disturb the spirit and the mind, a caution the modern wellness framing drops.
Where the tradition speaks to CBD at all, it is at the level of instinct: the right amount of a strong plant depends on the person and the purpose, and the potent parts of cannabis are to be used sparingly and for a reason. That sits beside the modern reading, where cannabidiol has a narrow set of uses backed by evidence and a wider set without. It is offered as a way of thinking, not a claim about the molecule.
Cautions For This Practice
Extra restraintEverything to be aware of is here, in one place. This practice suits most healthy people; a few situations call for real care.
CBD raised liver enzymes above five times normal in a third of adults at 1,500 mg a day, more so with valproate
Watkins 2021 gave 16 healthy adults a fixed 1,500 mg a day (about 20 mg/kg) for roughly 3.5 weeks; 44% (7 of 16) had ALT above the upper limit of normal and 31% (5 of 16) exceeded five times normal, meeting international drug-induced liver injury criteria and leading to discontinuation, with enzymes recovering on stopping. Dose-dependence comes from the Dravet and Lennox-Gastaut trials, where transaminase elevations were among the more notable adverse effects and concentrated in patients also taking valproate. The signal was strong enough that liver-function monitoring is part of the approved prescribing.Watkins et al., Cannabidiol and Abnormal Liver Chemistries in Healthy Adults: Results of a Phase I Clinical TrialDevinsky et al., Trial of Cannabidiol for Drug-Resistant Seizures in the Dravet Syndrome
CBD raised the active clobazam metabolite about 500%, forcing dose cuts in most children
Geffrey 2015 prospectively measured clobazam and N-desmethylclobazam levels in 13 children as cannabidiol was added. Levels of the active metabolite rose by a mean of about 500%, roughly five- to sixfold, via CYP2C19 inhibition, and 10 of 13 children had their clobazam dose lowered to manage sedation and other effects, while seizure control generally improved. This is a small, uncontrolled prospective series but a well-characterized, mechanistically expected interaction.Geffrey et al., Drug-drug interaction between clobazam and cannabidiol in children with refractory epilepsy
CBD raised one patient's warfarin effect, requiring about a 30% dose reduction
Grayson 2018 reported a 44-year-old man with post-stroke epilepsy (Marfan syndrome, mechanical mitral valve replacement), stable on warfarin, whose INR rose progressively as cannabidiol was titrated up, necessitating serial warfarin dose reductions of about 30% overall to keep the INR in range. Warfarin is metabolized largely by CYP2C9, which cannabidiol inhibits, making the interaction mechanistically expected. As a single case it is low-tier, but it is a documented, plausible, and clinically important warning for a drug where overshoot causes bleeding.Grayson et al., An interaction between warfarin and cannabidiol, a case report
Liver strain, especially with valproate
Cannabidiol can raise liver-enzyme readings, a sign of strain on the liver, and this was clear enough in the epilepsy trials that liver monitoring is built into prescription use. In a phase I trial, healthy adults given a fixed 1,500 mg a day saw liver enzymes climb, and about a third rose above five times the normal limit, meeting the criteria for drug-induced liver injury. The risk climbs higher again when cannabidiol is taken with valproate, an epilepsy drug. If you use cannabidiol at any meaningful dose, particularly alongside other medicines, liver-function testing is a reasonable precaution to raise with your clinician.
Drug interactions through CYP450
Cannabidiol inhibits several CYP450 liver enzymes that clear many common drugs, so it can push their blood levels up. A prospective study in children showed it raised the active form of clobazam, an anti-seizure drug, about fivefold, so most of the children needed their clobazam dose cut. A documented case showed it raised the effect of warfarin, a blood thinner, enough to need about a 30% dose reduction to keep the INR, a measure of blood-thinning, in its safe range. If you take an anticoagulant, an anti-seizure drug, or any medicine with a narrow safe range, do not start cannabidiol without checking the interaction with a pharmacist or clinician.
Label accuracy and THC contamination
The over-the-counter market is poorly regulated. When 84 online CBD products were tested, fewer than a third were labeled accurately for CBD content, and THC was detectable in about one in five. That means an uncertain dose and the chance of an unwanted psychoactive compound, which can also show up on a drug test. Buying only products with a recent third-party Certificate of Analysis is the practical defense.
Pregnancy, breastfeeding and children
Outside the specific prescription use for rare epilepsies under a specialist, cannabidiol has not been shown safe in pregnancy or breastfeeding, and regulators advise against it in those situations. Keep retail CBD products away from children, both for the unknowns and because of the THC and dosing uncertainty in unregulated products.
When you take other medicines or are unwell
Any use for a specific condition, any meaningful dose, and any use alongside prescription drugs belongs in a conversation with a clinician or pharmacist first. That is where the liver-enzyme monitoring, the interactions, and your own situation get weighed together.
Start slow, be smart, read the research, and consult a professional if you have any concerns. This is here to inform your choice, not make it for you.
Common Questions
Does CBD actually work, or is it hype?
Both, depending on the use. For three rare epilepsies, Dravet syndrome, Lennox-Gastaut syndrome and tuberous sclerosis complex, a prescription cannabidiol reduced seizures in randomized trials, and that evidence is strong. For acute, situational anxiety there is early single-dose evidence. For chronic pain and sleep, the two things it is most marketed for, the evidence is mixed and thin, well behind what the shelf implies. The strong uses are narrow and specific; the broad wellness promises are where the hype outruns the research.
Is store-bought CBD the same as the prescription kind?
No, and the difference matters. Prescription cannabidiol, Epidiolex, is a purified medicine made to a known strength and tested in trials. Over-the-counter hemp CBD is a supplement, made to no such standard, and when products were lab-tested, fewer than a third matched their labels and about one in five contained detectable THC. The trial evidence was built on the prescription form at controlled doses, so it does not automatically transfer to a retail oil or gummy of uncertain content.
Can CBD interfere with my medications?
Yes, and this is the caution to take most seriously. Cannabidiol acts on the CYP450 liver enzymes that clear many common drugs, so it can raise their levels in your blood. It raised the active form of the anti-seizure drug clobazam about fivefold in a study of children, and in a documented case it raised the effect of the blood thinner warfarin enough to require about a 30% lower dose. If you take an anticoagulant, an anti-seizure medicine, or anything with a narrow safe range, check with a pharmacist before starting CBD.
What dose of CBD helps with anxiety?
The experimental evidence points to a single moderate dose. In a controlled public-speaking test, 300 mg taken beforehand lowered anxiety while 150 mg and 600 mg did not, an inverted-U pattern where more is not better. This is short-term evidence about a stressful event, not about treating an anxiety disorder over time, so it belongs alongside established care, and check drug interactions before trying.
Does CBD help you sleep?
The best clinical report is thin. In an uncontrolled clinic series of 72 adults given CBD mostly for anxiety or sleep, sleep scores improved for about two-thirds in the first month, but the gains came and went and there was no comparison group. Much of the improvement appeared to follow lower anxiety rather than a direct sleep effect. The durable, free groundwork on the insomnia guide does more for most people than a supplement, so treat CBD for sleep as early and check drug interactions first if you try it.
Explore Related
Other pages this one connects to, by the evidence they share, the outcomes they touch, and the ground they cover.
All 12 sources on this page independently checked and cross-referenced.
Thomas Dehli, Founder & Editor, Sacred Lotus
Sacred Lotus has published Chinese medicine reference material since 2001. Integrative pages are held to the same standard as the herb and formula library: cite the source, grade the claim at its real strength, and say where the research has not looked. This page is educational and it is not medical advice. Last reviewed and updated August 9, 2026.
Evidence strength
How confidently the research supports a claim. Strength describes the evidence, not our endorsement.