CBD vs THC: What Cannabidiol Actually Is, and What the Evidence Actually Supports
CBD is cannabidiol — one of the two cannabinoids in cannabis that anyone outside a lab can name. It will not get you high the way THC does. Almost everything else the internet tells you about it needs a qualifier.
This guide covers what CBD is, how it differs from THC molecule by molecule, whether it is psychoactive, whether it cancels THC out, whether it shows on a drug test, what Canadian law says, and the single largest thing missing from every other page on this topic: the distance between the doses used in the research and the dose in a consumer product.
Key Takeaways
- CBD stands for cannabidiol. It has the same molecular formula as THC — C₂₁H₃₀O₂ — and a different shape, which is why it barely binds the receptor THC binds.[1]
- “Non-intoxicating” is correct. “Non-psychoactive” is not. CBD is centrally active, and in a controlled trial 400 mg of vaporised CBD produced measurable intoxication relative to placebo.[2]
- CBD does not reliably cancel THC out. In that same trial, a low 4 mg dose increased THC intoxication, most sharply in infrequent users. Only the 400 mg dose reduced it.[2]
- The dose gap is two orders of magnitude. Canada’s authorised CBD drug is maintained at 10 mg/kg/day.[3] A consumer gummy holds 10–25 mg.
- Food changes the dose you actually get. A high-fat meal raised peak CBD concentration roughly 14-fold and total exposure roughly 4-fold on an identical capsule.[4]
- Pure CBD did not produce a positive urine screen in a controlled study — CBD-dominant cannabis did.[5] The THC riding along is the variable, not the CBD.
- Canadian regulations cap THC in every product class and set no limit on CBD at all.[6] That is a composition rule, not an endorsement.
- We sell CBD and we are not going to tell you what it does for you. Section 132.28 of the Cannabis Regulations prohibits it, and honestly the evidence at consumer doses would not support it anyway.[7]
What Is CBD?
CBD stands for cannabidiol, a 21-carbon compound that is one of the most abundant cannabinoids in the cannabis plant.[1] That is the whole of the CBD meaning — a molecule, not a product category and not an effect.
In the living plant, CBD does not exist in the form you consume. The plant makes cannabidiolic acid (CBDA), which converts to cannabidiol when heated or aged. The same is true of THC, which starts as THCA. Both acids descend from the same precursor and split at a single enzymatic fork.[1]
What people mean by “CBD” in a shop is usually a product — CBD oil, a CBD tincture, CBD gummies, CBD flower, a CBD vape. Those are formats. The cannabidiol in each of them is the same molecule, and the differences between products come from dose, carrier and what else is in the bottle. Our CBD category is sorted by format for exactly that reason.
CBD vs THC: What Is the Actual Difference?
The difference between CBD and THC is not what they are made of — both are C₂₁H₃₀O₂ — but how the molecule folds. THC’s ring closes; CBD’s does not. That single structural difference decides whether it fits the CB1 receptor.[1]
Searched as CBD vs THC or as THC vs CBD, the comparison lands in the same place: one of them fits the receptor and one of them does not.
THC binds CB1 receptors in the brain directly, and that binding is what produces intoxication. CBD does not. The WHO’s critical review puts it plainly: CBD “does not appear to act directly at CB1 receptors, with a number of studies reporting that there is no measurable response in binding assays,” and it also shows low affinity at CB2.[1]
Instead, CBD works across a scatter of other targets — adenosine uptake, 5-HT1A receptors, glycine receptors — and appears to act as a negative allosteric modulator at CB1, meaning it changes how the receptor responds to something else binding it rather than switching it on itself.[1][8]
| CBD (cannabidiol) | THC (tetrahydrocannabinol) | |
|---|---|---|
| Molecular formula | C₂₁H₃₀O₂ | C₂₁H₃₀O₂ — identical[1] |
| Acid form in the plant | CBDA | THCA |
| CB1 receptor | No measurable direct binding response[1] | Direct agonist — this is the intoxication |
| Intoxicating? | No | Yes |
| Psychoactive? | Yes — centrally active[1] | Yes |
| Abuse or dependence potential | “No effects indicative of any abuse or dependence potential”[1] | Established |
| Capped by Canadian regulation? | No limit set[6] | Capped in every product class[6] |
| Shows on a standard urine screen? | Not in a controlled study of pure CBD[5] | Yes — that is what the test measures |
| Authorised as a drug in Canada? | Yes, one product, three seizure disorders[3] | In combination products only |
Does CBD Get You High?
No — but “non-psychoactive,” the phrase every CBD page uses, is the wrong word. A substance that crosses into the brain and changes how you feel is psychoactive by definition. The accurate term is non-intoxicating.
This is not pedantry. In a randomised controlled trial of vaporised cannabinoids, 400 mg of CBD administered alone produced measurable intoxication relative to placebo — small, but present on both objective and subjective measures.[2] That is a dose far above anything sold as a consumer product, and the effect is nothing like THC. It is still not zero.
The practical answer to “does CBD get you high” and “is CBD psychoactive” is: it does not produce the intoxication people mean by high, and it is not inert either. Anyone telling you a cannabinoid crosses the blood-brain barrier and does absolutely nothing is selling you a story about the molecule.
Does CBD Cancel Out THC?
Sometimes, at doses nobody sells, and it can run the other way. This is the most repeated claim in the topic and the one with the clearest evidence against the popular version of it.
The trial that tested it directly gave 36 participants vaporised THC alone (8 mg), THC with 4 mg of CBD, and THC with 400 mg of CBD. The high dose reduced intoxication. The low dose enhanced it — and the enhancement “was particularly prominent in infrequent cannabis users and was consistent across objective and subjective measures.”[2]
| Condition tested | CBD dose | Effect on THC intoxication[2] |
|---|---|---|
| THC alone | 0 mg | Reference point |
| THC + low-dose CBD | 4 mg | Increased — most sharply in infrequent users |
| THC + high-dose CBD | 400 mg | Reduced |
| CBD alone | 400 mg | Mildly intoxicating vs placebo |
Vaporised administration, n=36, frequent and infrequent users. A consumer “1:1” product sits far closer to the 4 mg row than the 400 mg row.
Older work did find CBD blunting some THC effects, and the WHO review notes that “some studies have shown that CBD may reduce or antagonize some of the effects of THC.”[1] The honest summary is that the direction depends on the ratio and the dose, and the ratios people actually buy have not been shown to protect anyone from a strong edible.
What this does not mean: it does not mean CBD makes THC worse. It means the relationship is dose-dependent and the “CBD will keep me level” plan is not supported at the doses in consumer products. If a dose is too strong, the fix is a smaller dose — see our edibles dosing guide.
How Much CBD Was Used in the Research?
Far more than is in anything you can buy. This is the single most important number in the topic and almost no page states it. Health Canada’s authorised CBD medicine is maintained at 10 mg/kg/day and can be titrated to 25 mg/kg/day.[3]
For a 70 kg adult that is roughly 700 mg a day at maintenance and up to about 1,750 mg at the ceiling. A consumer CBD gummy typically holds 10 to 25 mg. The research that establishes CBD does anything at all, for the one thing it is authorised for, ran at fifty to a hundred times a retail serving.
The CBD dose gap — four gaps that multiply
This is our framework, and it is what the “why did nothing happen” question below is built on. Four separate gaps sit between a clinical result and the bottle in your hand, and they compound rather than add.
| Gap | In the research | In a consumer product |
|---|---|---|
| 1. Dose | 700–1,750 mg/day for a 70 kg adult[3] | 10–25 mg per serving |
| 2. Absorption | Standardised food conditions, controlled timing[3] | Whenever, with whatever — a ~14× swing in peak concentration[4] |
| 3. Product | Pharmaceutical-grade oral solution, single known compound[3] | An extract with other cannabinoids and a carrier oil |
| 4. Endpoint | Seizure counts in three named syndromes[3] | Whatever the buyer is hoping for |
Any one of these would weaken an inference. Together they mean a result from the clinical literature cannot be carried across to a 20 mg tincture in either direction — it does not prove the tincture works, and it does not prove it fails. It simply was not the thing tested.
Why Does the Same CBD Dose Land Differently?
Because oral CBD is poorly and erratically absorbed, and food changes the result enormously. The same capsule, the same milligrams, taken fasted or after a fatty meal, is not the same delivered dose.
In adults with refractory epilepsy given identical CBD capsules, a high-fat meal raised peak blood concentration roughly 14-fold and total exposure roughly 4-fold compared with fasting.[4] An independent 2025 crossover trial using a broad-spectrum extract found the same direction at even larger magnitude, and shifted the time to peak from about 5 hours to about 10.[9]
That second study also notes the background figure that explains the whole problem: oral CBD bioavailability without a meal is on the order of 6%.[9] Most of what you swallow never reaches your bloodstream, and how much does depends on what else is in your stomach.
| Route | Onset | What drives the variability |
|---|---|---|
| Oral (capsule, gummy, edible) | Slow — hours[9] | Stomach contents, fat content, first-pass metabolism |
| Sublingual (tincture held under the tongue) | Faster than swallowed | How long you actually hold it; most people swallow too soon |
| Inhaled (CBD flower, CBD vape) | Minutes | Inhalation depth, device, combustion losses |
| Topical | Local application | Skin penetration is its own unresolved question — see our article on cannabis and skin |
The one practical instruction in this article: whatever you take, take it the same way every time. Consistency of conditions is worth more than precision of milligrams, because the conditions move the delivered dose by more than the label does.
What Are the Different Forms of CBD?
The formats — CBD oil, tinctures, gummies, capsules, flower, vapes, topicals — matter less than the three-way split between isolate, broad spectrum and full spectrum. That split decides whether there is any THC in the product at all.
CBD edibles, capsules and tinctures all go through the digestive tract and inherit the absorption problem below. Inhaled formats do not. Neither route changes what the cannabidiol is.
| Type | What is in it | THC present? | Matters because |
|---|---|---|---|
| CBD isolate | Purified cannabidiol, nothing else | No | The only format where “no THC” is a structural fact rather than a claim |
| Broad spectrum CBD | Multiple cannabinoids and terpenes, THC removed | Trace or none | “Removed” is a process claim — check the certificate of analysis |
| Full spectrum CBD | The whole extract as the plant made it | Yes, at low levels | This is the format that can produce a positive drug test[5] |
What about the “entourage effect”?
The argument for full spectrum is that the other compounds work together. It is plausible and it is under-evidenced. The one controlled test of whether cannabis terpenes modulate cannabinoid receptor signalling found that they did not.[10] That does not close the question — it does mean the marketing is well ahead of the data.
CBD flower
CBD flower is cannabis bred to express cannabidiol rather than THC, sold as bud and smoked or vaporised like any other flower. It is not a different plant and it is not exempt from anything. Whatever the cultivar name on the jar says, the chemistry is what the certificate says — article #2 covers why those labels are unreliable.
The same holds for the other formats. A CBD vape or cart is hardware plus an extract, with the hardware questions that come with it, and a CBD concentrate is made by the extraction routes covered in our concentrates pillar.
How Do You Read a CBD:THC Ratio?
A CBD:THC ratio is a statement about the chemistry in the package, not a promise about the experience. A 1:1 CBD:THC product contains equal milligrams of each. It does not contain a guarantee that one balances the other.
Canadian labels display total CBD and total THC — figures that account for the acid forms converting when the product is heated.[11] This is why a package can say 100 mg/g total CBD on flower that has almost no free CBD in it yet: the number describes what the material would yield, not what is sitting in the jar.
| On the label | What it means | What it does not mean |
|---|---|---|
| Total CBD | CBD plus what the CBDA would convert to on heating[11] | The amount your body absorbs |
| Total THC | Same calculation for THC and THCA[11] | How intoxicating a given serving will be |
| 1:1 CBD:THC | Equal milligrams of each cannabinoid | That the CBD cancels the THC[2] |
| 20:1 CBD:THC | A CBD-dominant product with real THC in it | That it cannot show on a drug test[5] |
| “THC-free” | A manufacturer’s claim about a process | A tested result — ask for the certificate |
Can You Trust a CBD Label?
In the Canadian regulated market, CBD label claims tested better than THC claims on the same products. In the unregulated market that produced the famous mislabelling statistic, they did not. Both facts are real and they describe different markets.
The statistic everyone quotes comes from 2017: 84 CBD extracts bought online from 31 companies, of which about 30% were within 10% of their labelled CBD content, roughly 43% held more than the label said and about 26% held less.[12] THC was detected in a number of them. That was an unregulated market with no mandatory potency testing.
The Canadian picture is different and more recent. Of 30 legal oral cannabis oil products tested in Ontario, 27 (90%) met the permitted 15% variance for CBD, while only 18 (60%) met it for THC.[13] The authors still concluded that “inaccurate labeling of cannabis oil products in the legal Canadian market is common.”[13]
| Study | Market | CBD accuracy | THC accuracy |
|---|---|---|---|
| 84 online extracts, 2017[12] | US, unregulated, no mandatory testing | ~30% within 10% of label | THC detected in a number of products |
| 30 oral oils, Ontario, 2024[13] | Canada, legal, mandatory testing | 90% within the 15% variance | 60% within the 15% variance |
Not the same design, not the same products, not comparable head to head. The point of putting them side by side is that “CBD labels are meaningless” is a 2017 statement about a market that no longer describes a Canadian buyer.
The honest read: a legal Canadian label is the best number available and still not exact, and a product with no label and no certificate has no number at all. That is the same conclusion our edibles guide reaches from different data.
Does CBD Show Up on a Drug Test?
Pure CBD did not, in the study that measured it directly. CBD-dominant cannabis did. This has been tested rather than guessed, which makes it one of the few questions in the topic with a clean answer.
Six adults received 100 mg of oral CBD, 100 mg of vaporised CBD, and vaporised CBD-dominant cannabis containing 100 mg CBD plus 3.7 mg of THC, with urine collected for five days. The pure CBD conditions produced no positive screens at the 50 ng/mL immunoassay cutoff. The CBD-dominant cannabis produced positives.[5]
The authors’ conclusion is worth quoting because it is narrower than the headline: acute dosing of pure CBD “will not result in a positive urine drug test using current federal workplace drug testing guidelines,” while products containing both CBD and THC may.[5] A standard test looks for a THC metabolite. It was never looking for cannabidiol.
So the risk is the format, not the cannabinoid. Isolate carries no THC by construction. Full spectrum carries some. Broad spectrum depends entirely on whether the removal step worked, which is what a certificate of analysis is for. If a drug test matters to your job, that certificate is the only thing that answers the question.
What Are CBD’s Side Effects and Drug Interactions?
The common CBD side effects reported in trials are drowsiness, decreased appetite, diarrhoea and fatigue. The more serious issue is not the molecule on its own — it is what it does to the metabolism of other drugs.[1][14]
CBD is extensively metabolised in the liver via CYP3A4 and CYP2C19, among others.[1] Those are the same enzymes that clear a long list of prescription medicines, which is why the interaction question is the real one. In one clinical series combining CBD with clobazam, side effects appeared in 10 of 13 subjects and were managed by reducing the other drug, not the CBD.[1] CBD interactions are the part of this topic worth taking seriously.
Health Canada’s Science Advisory Committee on Health Products Containing Cannabis reviewed this in 2022 and agreed unanimously that CBD “is safe and tolerable for short-term use (a maximum of 30 days) at doses from 20 milligrams per day to a maximum dose of 200 mg/day via oral administration for healthy adults.”[14]
| Finding | Source | What it means for a buyer |
|---|---|---|
| No abuse or dependence potential in humans | WHO ECDD, 2018[1] | Not a dependence risk in the way THC is |
| Drowsiness, decreased appetite, diarrhoea, fatigue | WHO ECDD, 2018[1] | The common complaints, mostly dose-related |
| Metabolised by CYP3A4 and CYP2C19 | WHO ECDD, 2018[1] | Genuine interaction potential with prescription drugs |
| Liver enzyme elevations, especially with valproate or clobazam | Health Canada, 2023[3] | Observed at clinical doses under monitoring |
| 20–200 mg/day, oral, up to 30 days, healthy adults | Health Canada SAC, 2022[14] | The clearest Canadian statement of a tolerable range |
| Beyond 30 days, consult a practitioner | Health Canada SAC, 2022[14] | The committee’s own recommendation, not ours |
If you take any prescription medication, this is a conversation with a pharmacist, not with a shop. We can tell you what is in a package. We cannot tell you how it interacts with your prescriptions, and nobody selling cannabis should pretend otherwise.
What Does the Evidence Actually Support?
One thing, at one dose range, for three specific conditions — and that is a regulatory fact, not our opinion or our sales pitch. Everything beyond it is an open question, and this page is not going to close it for you.
On 15 November 2023, Health Canada authorised a cannabidiol oral solution as adjunctive therapy for seizures associated with Lennox-Gastaut syndrome, Dravet syndrome and tuberous sclerosis complex, in patients aged two and older.[3] That authorisation followed Phase III trials, which the WHO review had already noted.[1]
That is a prescription medicine dosed by body weight under supervision. It is not evidence about a 20 mg gummy, for the four reasons set out in the dose gap above. Where the evidence for a consumer-scale question has been looked at directly — CBD and skin, for instance — the result has generally been that nobody has looked properly yet.[15]
Why we are not going to tell you what CBD does
Two reasons, and the first one is not the interesting one. Section 132.28 of the Cannabis Regulations prohibits any representation that “could create the impression that health or cosmetic benefits may be derived from the use of the cannabis product.”[7] A Canadian retailer making a CBD effects claim is breaking a specific rule.
The second reason is that we could not support it if we were allowed to. Health Canada has said there is currently no legal pathway to market a natural health product containing CBD, and its own advisory committee stopped at “safe and tolerable,” not at what it does.[14][16] A shop that fills that gap with confident copy is inventing the part everyone actually wants.
Is CBD Legal in Canada?
Yes, and it is regulated as cannabis — not as a supplement, not as a food, and not differently because it came from hemp. Every phytocannabinoid including CBD falls under the Cannabis Act regardless of the plant it was extracted from.[16]
This is where Canada and the United States diverge sharply, and where most of the confusion in the topic comes from. There is no “hemp CBD” carve-out here that lets a wellness brand put cannabidiol in a bottle and sell it beside the vitamins. Health Canada is explicit that no legal pathway currently exists for a natural health product containing CBD.[16]
The composition rules contain a detail almost nobody knows. THC is capped in every class — 10 mg per immediate container for edibles, 1,000 mg per container for extracts and topicals. For CBD, Health Canada states plainly that “the Act and Regulations do not set limits on the amount of other cannabinoids, including CBD.”[6]
| Product class | THC limit[6] | CBD limit[6] |
|---|---|---|
| Edible cannabis | 10 mg per immediate container | None set |
| Cannabis extracts | 1,000 mg per container; 10 mg per discrete ingestible unit | None set |
| Cannabis topicals | 1,000 mg per container | None set |
| Dried flower | Not capped; total THC must be labelled | None set; total CBD must be labelled[11] |
“No limit set” is a statement about composition rules. It reflects that CBD is not treated as an intoxicant for capping purposes — it is not a safety endorsement of any particular dose.
How Do You Choose a CBD Product?
Work backwards from two questions: does any THC in it create a problem for you, and how consistently can you take it? Everything else — flavour, format, brand — is preference.
There is no evidence-based CBD dosage for a general consumer, because the endpoint has not been defined. What exists is Health Canada’s tolerability range and the observation that conditions move the delivered dose more than the label does.[14][4]
| If you… | Look at | Because |
|---|---|---|
| Are subject to workplace drug testing | CBD isolate, with a certificate of analysis | It is the only format with no THC by construction[5] |
| Take prescription medication | A pharmacist, before a product | CYP3A4 and CYP2C19 interactions are real[1] |
| Want the most consistent dose | Capsules or measured gummies, taken with the same meal | Fixed units plus fixed conditions removes two variables[4] |
| Want it to land quickly | Inhaled — CBD flower or a vape | Minutes rather than hours, and no food effect |
| Want to titrate finely | A CBD oil or tincture with a graduated dropper | You can move in small increments |
| Are combining it with THC | The THC number first | The THC decides the intoxication; the CBD will not offset it[2] |
CBD Myths, Checked
Five claims that appear on nearly every CBD page, and what the evidence says about each.
| The claim | Status | What is actually the case |
|---|---|---|
| “CBD is non-psychoactive” | Wrong word | It is non-intoxicating. It is centrally active, and 400 mg produced mild intoxication versus placebo[2] |
| “CBD cancels out THC” | Dose-dependent, sometimes backwards | 4 mg increased THC intoxication; 400 mg reduced it[2] |
| “CBD can’t show on a drug test” | Depends on the product | Pure CBD produced no positives; CBD-dominant cannabis did[5] |
| “Hemp CBD is not regulated as cannabis” | False in Canada | All phytocannabinoids fall under the Cannabis Act regardless of source[16] |
| “CBD converts to THC in your stomach” | Not shown in humans | “There is no evidence that this transformation occurs in humans after oral CBD administration”[1] |
Frequently Asked Questions
What is CBD?
CBD stands for cannabidiol, a 21-carbon compound and one of the most abundant cannabinoids in cannabis. It shares its molecular formula with THC but folds into a different shape, which is why it does not bind the CB1 receptor the way THC does. In the plant it exists as CBDA and converts when heated or aged.
Does CBD get you high?
No. CBD is non-intoxicating, and it does not produce the effect people mean by high. It is not inert either — in a controlled trial, 400 milligrams of vaporised CBD produced mild measurable intoxication compared with placebo. That is far above any consumer dose. Non-intoxicating is accurate; non-psychoactive is the wrong word.
What is the difference between CBD and THC?
Both are C₂₁H₃₀O₂, so the difference is structural rather than compositional. THC’s ring closes and lets it bind CB1 receptors directly, which produces intoxication. CBD’s does not, so it acts through other targets instead. Canadian regulations cap THC in every product class and set no limit at all on CBD.
Does CBD show up on a drug test?
In the study that tested this directly, pure CBD taken orally or vaporised produced no positive urine screens at the standard 50 ng/mL cutoff. CBD-dominant cannabis containing 3.7 milligrams of THC did produce positives. Standard tests look for a THC metabolite, so the format determines the risk, not the cannabidiol itself.
How much CBD should you take?
There is no evidence-based figure for general consumer use, because no endpoint has been defined. Health Canada’s advisory committee concluded CBD is safe and tolerable for healthy adults at 20 to 200 milligrams a day orally for up to thirty days. Beyond thirty days, the committee recommended consulting a health care practitioner.
Does CBD cancel out THC?
Not reliably, and it can run the other way. In a randomised trial of vaporised cannabinoids, adding four milligrams of CBD increased THC intoxication, most sharply in infrequent users, while four hundred milligrams reduced it. Consumer one-to-one products sit far nearer the low dose. If a dose feels too strong, take less THC.
Is CBD legal in Canada?
Yes, and it is regulated as cannabis rather than as a supplement. Every phytocannabinoid including CBD falls under the Cannabis Act regardless of whether it was extracted from hemp. Health Canada states there is currently no legal pathway to market a natural health product containing CBD, which is why it is not sold beside vitamins.
What is the difference between full spectrum, broad spectrum and isolate?
Isolate is purified cannabidiol with nothing else in it. Broad spectrum keeps other cannabinoids and terpenes but has had THC removed. Full spectrum is the whole extract, THC included at low levels. Isolate is the only one where the absence of THC is structural rather than a manufacturer’s process claim worth verifying.
Should you take CBD with food?
Food changes the result substantially. In adults given identical CBD capsules, a high-fat meal raised peak blood concentration around fourteen-fold and total exposure around fourfold versus fasting. The practical instruction is consistency rather than a rule: take it the same way every time, because conditions move the delivered dose more than the label does.
What are the side effects of CBD?
Trials commonly report drowsiness, decreased appetite, diarrhoea and fatigue. The World Health Organization found no evidence of abuse or dependence potential in humans. The more significant issue is metabolic: CBD is processed by liver enzymes including CYP3A4 and CYP2C19, so anyone on prescription medication should speak with a pharmacist first.
References
- World Health Organization, Expert Committee on Drug Dependence. Cannabidiol (CBD) Critical Review Report. Fortieth Meeting, Geneva, 4–7 June 2018. who.int (Chemistry and receptor pharmacology; “CBD does not appear to act directly at CB1 receptors”; “In humans, CBD exhibits no effects indicative of any abuse or dependence potential”; clobazam interaction in 10 of 13 subjects; hepatic metabolism via CYP3A4 and CYP2C19; no evidence of CBD-to-THC conversion in humans after oral administration.)
- Solowij, N., Broyd, S., Greenwood, L.-M., et al. A randomised controlled trial of vaporised Δ9-tetrahydrocannabinol and cannabidiol alone and in combination in frequent and infrequent cannabis users: acute intoxication effects. European Archives of Psychiatry and Clinical Neuroscience, 2019, 269, 17–35. DOI: 10.1007/s00406-019-00978-2 (n=36; five vaporised conditions — placebo, CBD 400 mg, THC 8 mg, THC + CBD 4 mg, THC + CBD 400 mg. Low-dose CBD enhanced THC intoxication, “particularly prominent in infrequent cannabis users”; high-dose CBD reduced it; CBD alone showed some intoxicating properties relative to placebo.)
- Health Canada. Regulatory Decision Summary — EPIDIOLEX (cannabidiol oral solution). Drug and Health Products Portal, authorised 15 November 2023. dhpp.hpfb-dgpsa.ca (Adjunctive therapy for seizures associated with Lennox-Gastaut syndrome, Dravet syndrome and tuberous sclerosis complex, aged 2 and over. Starting dose 5 mg/kg/day; maintenance 10 mg/kg/day; maximum 25 mg/kg/day. Transaminase elevations, particularly with concomitant valproic acid or clobazam; product to be taken under consistent food conditions.)
- Birnbaum, A. K., Karanam, A., Marino, S. E., Barkley, C. M., Remmel, R. P., Roslawski, M., Gramling-Aden, M., & Leppik, I. E. Food effect on pharmacokinetics of cannabidiol oral capsules in adult patients with refractory epilepsy. Epilepsia, 2019, 60(8), 1586–1592. DOI: 10.1111/epi.16093. PMID: 31247132. (Eight patients; 99% pure CBD capsules fasted versus after a high-fat meal of 840–860 calories. Cmax approximately 14 times higher and AUC₀₋∞ approximately 4 times higher in the fed state. Publisher page returned 403 from a cloud run; citation and figures confirmed from the University of Minnesota institutional repository record.)
- Spindle, T. R., Cone, E. J., Kuntz, D., Mitchell, J. M., Bigelow, G. E., Flegel, R., & Vandrey, R. Urinary Pharmacokinetic Profile of Cannabinoids Following Administration of Vaporized and Oral Cannabidiol and Vaporized CBD-Dominant Cannabis. Journal of Analytical Toxicology, 2020, 44(2), 109–125. DOI: 10.1093/jat/bkz080 (Six adults, crossover; 100 mg oral CBD, 100 mg vaporised CBD, and vaporised CBD-dominant cannabis with 100 mg CBD plus 3.7 mg THC. Pure CBD produced no positive screens at the 50 ng/mL cutoff; the CBD-dominant cannabis condition did.)
- Health Canada. Guide on composition requirements for cannabis products. canada.ca (Edible cannabis: THC must not exceed 10 mg per immediate container. Extracts and topicals: 1,000 mg THC per immediate container; 10 mg THC per discrete unit for ingestion. “The Act and Regulations do not set limits on the amount of other cannabinoids, including CBD.”)
- Cannabis Regulations (SOR/2018-144), s. 132.28 — Prohibited representation — health and cosmetic benefits. laws-lois.justice.gc.ca (Prohibits any express or implied representation, including by brand element, if there are reasonable grounds to believe it could create the impression that health or cosmetic benefits may be derived from the use of the cannabis product.)
- Khurana, L., Mackie, K., Piomelli, D., & Kendall, D. A. Modulation of CB1 Cannabinoid Receptor by Allosteric Ligands: Pharmacology and Therapeutic Opportunities. Neuropharmacology, 2017, 124, 3–12. DOI: 10.1016/j.neuropharm.2017.05.018. PMID: 28527758. (Review confirming CBD “can act as a negative allosteric modulator of CB1 signaling,” detected in multiple systems at CBD concentrations between 500 nM and 1000 nM. The primary report is Laprairie et al., British Journal of Pharmacology 2015, DOI 10.1111/bph.13250, PMID 26218440 — the publisher page returned 403 from a cloud run, so it is cited here through this review rather than read directly, and volume and page numbers are deliberately not stated.)
- Saals, B. A. D. F., De Bie, T. H., Osmanoglou, E., van de Laar, T., Tuin, A. W., van Orten-Luiten, A. C. B., & Witkamp, R. F. A high-fat meal significantly impacts the bioavailability and biphasic absorption of cannabidiol (CBD) from a CBD-rich extract in men and women. Scientific Reports, 2025, 15, 3678. DOI: 10.1038/s41598-025-87621-4 (Randomised crossover, 11 healthy participants, 70 mg CBD as a broad-spectrum extract. Cmax geometric mean ratio 17.4 and AUC ratio 9.7 fed versus fasted; Tmax shifted from about 5 to about 10 hours. Cites prior literature putting oral CBD bioavailability at approximately 6% without a meal.)
- Finlay, D. B., Sircombe, K. J., Nimick, M., Jones, C., & Glass, M. Terpenoids From Cannabis Do Not Mediate an Entourage Effect by Acting at Cannabinoid Receptors. Frontiers in Pharmacology, 2020, 11, 359. DOI: 10.3389/fphar.2020.00359
- Health Canada. Packaging and labelling guide for cannabis products and Displaying THC and CBD content on dried cannabis product labels and kief. canada.ca (Total THC and total CBD must appear on the principal display panel, calculated taking into account the potential to convert THCA into THC and CBDA into CBD. Labels must reflect certificate-of-analysis results for the lot and must not be false, misleading or deceptive.)
- Bonn-Miller, M. O., Loflin, M. J. E., Thomas, B. F., Marcu, J. P., Hyke, T., & Vandrey, R. Labeling Accuracy of Cannabidiol Extracts Sold Online. JAMA, 2017, 318(17), 1708–1709. DOI: 10.1001/jama.2017.11909. PMID: 29114823. (84 products from 31 companies; approximately 30% within 10% of the labelled CBD content, about 43% under-labelled and about 26% over-labelled; THC detected in a number of products. Context caveat: the 2017 US online market, with no mandatory potency testing. Citation verified from the Johns Hopkins institutional record; the quantitative figures were confirmed from a press summary rather than the paper itself, and the exact THC detection rate is deliberately not stated.)
- Doggett, A., Fein, A., Campbell, T., Henriquez, N., Busse, J. W., & MacKillop, J. Label Accuracy of Legal Oral Cannabis Oil Products in Ontario, Canada. JAMA Network Open, 2024, 7(6). DOI: 10.1001/jamanetworkopen.2024.14922. PMID: 38837163. (30 legal oral cannabis oil products; 27 of 30 within the permitted 15% variance for CBD versus 18 of 30 for THC; 10 of 30 showed website-versus-label discrepancies. Authors’ conclusion: “inaccurate labeling of cannabis oil products in the legal Canadian market is common.”)
- Health Canada, Science Advisory Committee on Health Products Containing Cannabis. Review of Cannabidiol. 28 July 2022. canada.ca (Committee agreed unanimously that CBD “is safe and tolerable for short-term use (a maximum of 30 days) at doses from 20 milligrams per day to a maximum dose of 200 mg/day via oral administration for healthy adults”; recommended labelling on interactions with other drugs and alcohol; recommended practitioner consultation beyond 30 days.)
- Sermsaksasithorn, P., et al. Cannabis and cannabinoids in dermatology: a systematic review and meta-analysis of quantitative outcomes. Frontiers in Pharmacology, 2025, 16, 1609667. DOI: 10.3389/fphar.2025.1609667 (17 studies, 11 randomised, 3,359 participants. Authors state cannabinoids “should not yet be recommended as standalone treatments for dermatologic conditions.” Cited here only as an example of what happens when a consumer-scale CBD question is examined directly; the detail is in our cannabis and skin article.)
- Health Canada. Towards a pathway for health products containing cannabidiol: natural health products containing cannabidiol, and Notice to Stakeholders: Non-Prescription Health Products Containing Cannabidiol (CBD), 28 July 2022. canada.ca (All phytocannabinoids including CBD fall under the Cannabis Act regardless of source; “there is no legal pathway to market a natural health product containing CBD”; Health Canada is exploring a potential framework and no non-prescription CBD health product is authorised in the interim.)
This article is for informational purposes only and is not medical advice. Speak with a pharmacist or physician before combining cannabidiol with prescription medication. Do not drive after using cannabis. Keep all cannabis products locked away from children and pets. Follow the cannabis laws applicable in your jurisdiction.