What is CBD? Origin, THC difference, and how to choose

CBD, or cannabidiol, is a molecule that occurs naturally in hemp. It is one of roughly a hundred cannabinoids identified in the plant. Its defining feature — and the reason it is legal where cannabis is not: it does not get you high.

The World Health Organization’s expert committee established this in 2018, when it recommended that pure CBD not be placed under international control.

CBD and THC: the difference that matters

Both molecules come from the same plant and have — surprisingly — exactly the same chemical formula: C₂₁H₃₀O₂. The only thing separating them is how their atoms are arranged in space.

That difference changes everything, because it determines how each molecule binds to receptors in the nervous system.

That last row causes the most trouble: a compliant CBD product lawfully contains trace THC, and roadside tests look for THC, not CBD. The legality of your purchase is not a defence under traffic law.

Where the CBD you buy comes from

Commercial CBD is extracted from industrial hemp varieties: cultivars selected for naturally low THC and listed on an official register. They are not the same plants grown for recreational use.

The most common process is supercritical CO₂ extraction, which recovers the compounds without leaving solvent residue. Others exist — ethanol, for instance — and are not worse, provided the certificate of analysis confirms no residual solvents in the finished product.

That is, in fact, the only angle from which extraction method should interest you as a buyer: not as a marketing claim, but as something the lab report has to confirm.

Full spectrum, broad spectrum, isolate

The concept that confuses newcomers most, and the one that decides most in practice.

Full spectrum. Contains all the plant’s compounds: cannabinoids, terpenes, flavonoids — and therefore trace THC, below the legal limit.

Broad spectrum. The same compounds, with the THC removed during processing.

Isolate. Purified CBD, separated from everything else. No other cannabinoids, no terpenes, no THC.

This is not a quality question — all three profiles can be excellent or mediocre. It is a constraint question:

• You drive regularly, or you get tested → isolate is the only profile that excludes THC by construction. Broad spectrum works if the batch certificate confirms it.
• You want the plant’s complete profile → full spectrum.

Reading a label without being misled

Three numbers appear on these products, and they do not say the same thing.

The percentage (10%, 20%) gives concentration, not quantity.

Total milligrams tells you how much CBD is in the container. That is the useful number: 10 ml at 10% = 1,000 mg.

Price per milligram is the only honest way to compare. A 10 ml bottle at 5% (500 mg) for €30 works out at €0.060/mg. A 30 ml bottle at 10% (3,000 mg) for €90 works out at €0.030/mg: half the price, while looking three times more expensive on the shelf.

That is why we show price per milligram on every product we list. It is not a claim, it is arithmetic — and it is the number most shops do not show.

The certificate of analysis

A serious product comes with a certificate of analysis matching its batch. Issued by an independent laboratory, it states actual CBD content, THC content, and the absence of contaminants: heavy metals, pesticides, residual solvents.

Two checks are worth making: the batch number on the certificate must match the label, and the date must correspond to that production run. A generic brand analysis tells you nothing about the bottle in your hand.

Without a batch certificate, no figure on the packaging can be verified.

What is known about safety, and what is not

Two things are true at once, and most pages report only one of them.

The WHO concluded in 2018 that pure CBD is not psychoactive and does not produce dependence.

The EFSA, by contrast, has not been able to establish the safety of regular oral consumption. It identified data gaps in 2022 and confirmed that position in 2025: a provisional reference point in the order of 2 mg per day, and the finding that safety cannot be established for people under 25, for pregnant or breastfeeding women, or for anyone on medication.

That last point is the most concrete. CBD is metabolised by liver enzymes that also process a great many medicines, which can change how much of a drug ends up in your bloodstream — in either direction. If you take medication, that question belongs with your doctor or pharmacist, not with a website, including this one.

How the plant makes CBD

Knowing where the molecule comes from defuses half the sales arguments you will meet, because most of them are about one step in this process.

It all starts with CBGA

Hemp does not make CBD directly. It makes a precursor first — CBGA, cannabigerolic acid, often called the mother cannabinoid. Enzymes then convert it, depending on the variety, into CBDA, THCA or CBCA. The plant’s genetics decide the ratio: an industrial hemp variety sends almost all of the CBGA to CBDA and very little to THCA, which is exactly what makes it usable in law.

What the plant actually contains is CBDA

On the stem, the molecule exists in its acid form. CBD only appears once the carboxyl group is lost, through heat or simply through time. That is decarboxylation.

The 0.877 factor

That carboxyl group has mass. The ratio of molar masses between CBD and CBDA is about 0.877: when the group leaves as carbon dioxide, roughly 12 % of the material goes with it.

A laboratory therefore reports total CBD = CBD + (CBDA × 0.877). This is why two certificates for the same product can show two different numbers without anyone lying: one gives raw CBD, the other the total after decarboxylation. On a flower or a raw extract the gap easily reaches a fifth.

Why it matters at the till

Because comparing the “CBD” on one label with the “total CBD” on another is comparing two different quantities. The same arithmetic applies to THC — and total THC is the figure the legal limit is measured against.

Price per milligram, and the label tricks that block it

This is the number almost no shop shows, and without it comparing two bottles is guesswork.

Why a percentage tells you nothing

A percentage is a concentration, not a quantity and not a price. A 30 ml bottle at 10 % holds six times the CBD of a 10 ml bottle at 5 %, and works out at half the price per milligram — while looking three times more expensive on the shelf.

The calculation

Multiply volume in millilitres by concentration: 10 ml × 10 % = 1,000 mg. Then divide the price by that number. The result is currency per milligram, and it is the only figure that compares across brands.

Where the arithmetic is made impossible

When a label states an “extract content” instead of a CBD content, or a percentage with no volume. Both block the calculation, and both are a packaging design decision rather than an accident.

What “0 % THC” is, and is not

It is a claim, not a measurement. The measurement lives in the certificate, with its limit of quantification. Without that limit, 0.001 % and 0.05 % appear identical on the page — and if you are buying because of a drug test, that is the only line that matters.

What the research says, and what it does not

The honest answer is uncomfortable, which is exactly why it deserves precise wording.

What is well described

The chemistry: biosynthesis, the effect of heat and time, how the molecules behave during extraction and storage. All of it measurable, and measured.

What is less well described

Human physiology. The European Food Safety Authority listed data gaps in 2022 covering the liver, the gastrointestinal tract, the endocrine and nervous systems and reproduction.

The number from 9 February 2026

In its update, EFSA gives a provisionally safe intake level of 0.0275 mg per kilogram of body weight per day — about 2 mg a day for a 70 kg adult. A 10 % oil delivers roughly 5 mg per drop, so the EFSA figure is less than one drop.

The comparison that shows the uncertainty

The UK committee ACNFP works with 10 mg a day. Two serious authorities, two methods, a factor of five between them. That gap is the best available indicator of how open the file still is — and a reason to distrust any number presented as settled, in either direction.

Hemp and cannabis are the same species

The distinction is legal and commercial, not botanical, and the confusion around it explains half the contradictory information online.

One plant, two regimes

Cannabis sativa L. is a single species. “Hemp” and “cannabis” name the two sides of a legal threshold. Above it, the same plant changes category without changing species.

Why the threshold is arbitrary and still necessary

Because it has to fall somewhere, and every value is a policy choice. Czechia applies 1 %, the Netherlands tolerate 0.05 % in the product, most of the EU sits at 0.2 or 0.3 %. None of these follows from the biology of the plant.

What that changes when you buy

That “is this hemp or cannabis?” has no answer without naming the country and reading the lab result. The batch certificate answers it with a number; the name on the box does not answer it at all.

The milligrams on the label are not the milligrams that arrive

A 10 ml bottle at 10 % holds about 1,000 mg of CBD. A dropper holds roughly 25 mg. Almost every page stops there, as though 25 mg on the spoon were 25 mg in the bloodstream.

It is not, and the gap is not small. How you take it changes how much arrives by a factor of five or more — which makes the route as important as the number on the box, and it is almost never on the box.

Swallowed: most of it never gets past the liver

Anything swallowed — capsules, gummies, a drink, oil chased with water — goes through the gut and then the liver before reaching the bloodstream. The liver removes a large share on the way past. This is called first-pass metabolism, and for CBD it is severe: published pharmacokinetic studies put oral bioavailability in the region of 6 %, with wide variation between individuals.

Of a 25 mg capsule, then, something like 1.5 mg reaches circulation. The other 23.5 mg were real and were paid for; they simply never arrived.

Under the tongue: better, if you actually hold it there

Oil held under the tongue is absorbed partly through the mucous membrane, which drains into circulation without passing the liver first. Studies put sublingual bioavailability at roughly 13 % to 19 % — two to three times the swallowed route.

The catch is behavioural. That figure assumes the oil stays under the tongue for a minute or more. Swallowed after five seconds, it is an oral dose with extra steps, and you are back to 6 %.

With food, and why that is not a detail

CBD is fat-soluble. Taken with a high-fat meal, oral absorption rises sharply — the summary of product characteristics for the EU’s only authorised CBD medicine reports an increase of around four to five times compared with the fasted state.

Read that number again, because of what it means in practice: the same product, the same dose, can deliver four times more or less depending on whether you had breakfast. Any page that gives you a milligram figure without mentioning this is giving you a number that moves.

What this changes

It does not tell you how much to take — that is a question for a health professional, and the official position across Europe is that safety has not been established. What it tells you is narrower and more useful: a comparison between two products is only honest if the route is the same. Comparing a capsule’s milligrams with an oil’s milligrams compares two different things with the same unit.

The interaction that is not printed on the box

If you take any prescribed medicine, this is the section that matters more than everything above it, and it is the section most CBD pages leave out.

The same enzymes, the same queue

CBD is broken down in the liver by cytochrome P450 enzymes, chiefly CYP3A4 and CYP2C19. Those enzymes are not dedicated to CBD. They also process an estimated majority of prescription medicines in common use.

When two substances compete for the same enzyme, one of them waits. The one that waits builds up in the blood beyond what its dose was calculated for. That is the whole mechanism, and it works in both directions: CBD can raise the level of another drug, and other drugs can raise the level of CBD.

The grapefruit comparison is not a metaphor

You may have seen a warning on a medicine box about grapefruit juice. Grapefruit inhibits CYP3A4. That is the same enzyme, and the same reason for the same warning.

The comparison is useful because it makes the scale intuitive: nobody thinks grapefruit is dangerous, and yet the warning is printed on the box, because the interaction is real and the consequence lands on the medicine, not on the fruit. CBD is in that category.

Where this evidence comes from

Not from a supplement brand. Epidyolex is the only CBD-based medicine authorised in the European Union, and like every authorised medicine it carries a summary of product characteristics published by the European Medicines Agency. That document lists the interactions, the affected enzyme pathways and the liver monitoring its use requires.

It concerns a purified, high-dose pharmaceutical preparation, not a food supplement, and the doses are far higher than anything on a shop shelf. But it is the one place where the pharmacology has been examined to a regulatory standard, and it is public. When we say the interaction is documented, that document is what we mean.

What to do with this

Ask a pharmacist. Not us, not a forum, not the shop selling the bottle. A pharmacist has your medication list and can look up the pathway in seconds, which is the whole reason the profession exists.

The EFSA made the same point in narrower language when it stated that safety could not be established for people taking medication. That is not a warning about CBD being dangerous. It is a statement that the interaction question has not been answered, and an unanswered question is not the same as a negative answer.

What the words on the front actually mean

Front-of-pack language is where marketing lives, because the back of the pack is where the law lives. It is worth knowing which words carry a definition and which carry nothing.

“Lab tested” — nothing, on its own

Every product has been tested at some point by someone. The phrase commits to nothing: not which laboratory, not which batch, not what was measured, not what came back.

The version that means something is a certificate of analysis for the batch number on your bottle, from a third-party laboratory, dated. If the phrase appears and the certificate does not, the phrase is decoration.

“Organic” — regulated, but not about what you think

In the EU this one is real. Organic certification is governed by Regulation (EU) 2018/848 and the leaf logo requires an accredited control body and a code number on the label.

What it certifies is the agriculture: how the hemp was grown. It says nothing about the extraction, nothing about the CBD content, and nothing about whether the batch was tested. Organic hemp badly extracted is still badly extracted.

“Premium”, “pure”, “natural” — no definition anywhere

None of these has a legal definition for CBD products in any of our markets. They can be applied to anything by anyone. “Pure” is the most misleading of the three, because it sounds like a purity figure and is not one — a purity figure is a percentage on a certificate.

“Full spectrum” — a real term, unverifiable without the certificate

Full spectrum has a genuine technical meaning: the extract retains the plant’s other cannabinoids and terpenes, including trace THC. But nothing on the front of the box can show you that. Only the cannabinoid profile in the batch certificate can, and when that profile shows CBD and nothing else, the word on the front was wrong.

Why the certificate has a date, and why yours matters

A certificate of analysis is a photograph of one batch on one day. Two things make the date part of the information rather than a formality.

CBD becomes CBN, slowly

Cannabinoids degrade. Exposed to light, heat and oxygen, CBD and THC oxidise; THC in particular converts towards CBN, cannabinol. The process is slow at room temperature in a dark glass bottle and fast on a sunny shelf.

This is why oils come in amber or violet glass rather than clear, and why the storage line on the back is not filler. A bottle stored above a stove for a year is not the bottle the certificate describes.

The carrier oil is not neutral either

CBD is not sold neat. It is dissolved in a carrier, usually MCT (fractionated coconut), hemp seed oil, or olive oil. The carrier decides the taste, the shelf life, and how consistent the drops are — a thicker oil forms larger drops, so “a drop” is not a fixed quantity across products.

Hemp seed oil in particular is often confused with CBD oil in listings, including by sellers. Hemp seed oil is pressed from the seed and contains essentially no cannabinoids: the seed is not where the plant makes them. A product sold as “hemp oil” with no CBD figure and no certificate is frequently exactly that — a culinary oil at a cosmetic price.

What to check in ten seconds

Batch number on the bottle matching the certificate. A date within the product’s stated shelf life. A named laboratory that is not the seller. A cannabinoid profile with figures, not ticks. If any one of those is missing, the others do not compensate.

Frequently asked questions

Does CBD get you high? No. The WHO concluded in 2018 that pure CBD is not psychoactive in the sense of controlled substances.

What is the difference between CBD and THC? They share the same chemical formula but differ in the spatial arrangement of their atoms, which changes how they bind to receptors in the nervous system. THC is psychoactive and controlled; CBD is not.

What does full spectrum mean? That the product contains all the plant’s compounds, including trace THC below the legal limit. Broad spectrum removes the THC; isolate contains CBD only.

Which profile should I choose if I drive? Isolate, which excludes THC by construction. Broad spectrum works if the batch certificate confirms the absence of THC.

How do I compare two CBD products? By price per milligram: divide the price by the total CBD content in milligrams. Percentage alone allows no comparison at all.

Is CBD safe? The WHO found no dependence potential. The EFSA could not establish the safety of regular oral consumption, particularly for people under 25, pregnant or breastfeeding women, and anyone taking medication.