CBD vs THC: What's the Difference in UK Law?

CBD and THC come from the same plant, and UK law treats them in opposite ways. THC is a Class B controlled drug, carrying up to five years for possession and fourteen for supply. CBD, on its own, is not controlled at all.

That single split is most of the difference between CBD and THC in UK law, and the real answer to the CBD vs THC question. It is why a bottle of CBD oil can sit in a Hackney chemist while cannabis cannot, and why the same bottle can still become a criminal matter if the THC in it goes over a line most people have never been told about. The law draws that line in five separate places, and they do not all agree on where it sits.

Why is THC controlled and CBD not?

Because of how the Misuse of Drugs Act 1971 is written. Part II of Schedule 2, the Class B list, names cannabis and cannabis resin, cannabinol, and "cannabinol derivatives". Part IV defines those derivatives as the tetrahydro derivatives of cannabinol and their close chemical relatives. Tetrahydrocannabinol is exactly that, which is how THC ends up in Class B even when it has been extracted from the plant.

Cannabidiol is not on the list. Nobody voted to make CBD legal; it was simply never named, and the Home Office confirms in its drug licensing factsheet that pure, isolated CBD is not a controlled drug.

The reason for the difference is not mysterious. THC is the compound that makes cannabis intoxicating, and the 1971 Act was built to control intoxicants. CBD does not do that, so it fell outside. Everything else in this post is the consequence of a definition written over fifty years ago.

CBD vs THC under UK law, side by side

Most pages on this question stop at the Misuse of Drugs Act. The difference reaches further than that, into road traffic law, food law and medicines law, each run by a different part of government. Here is where each compound sits.

Area of law	CBD	THC
Misuse of Drugs Act 1971, Schedule 2	Not listed, so not controlled	Class B, as a cannabinol derivative
Exempt product rule, Misuse of Drugs Regulations 2001	Irrelevant to CBD itself	At most one milligram per component part, one of three conditions
Drug driving, specified limits	No limit set, because it is not a specified drug	2 microgrammes per litre of blood
Food law, Food Standards Agency	A novel food since 2019, with no product yet fully authorised	Controlled above the exempt product threshold
Licensed medicines, per the NHS	Epidyolex, a purified CBD liquid with no THC, can be prescribed	Sativex, licensed for one condition; others need a specialist prescription

Read down the THC column and the pattern is consistent: controlled everywhere, with narrow, named exceptions. The CBD column is messier. It is legal as a substance and still unauthorised as a food, which is the gap we covered in more detail in whether CBD is legal in the UK.

What does drug-driving law say about THC and CBD?

This is the row most CBD vs THC explainers leave out, and it is the one with the sharpest edge. Section 5A of the Road Traffic Act 1988, in force in England and Wales since 2 March 2015, makes it an offence to drive, attempt to drive or be in charge of a vehicle with a specified controlled drug in the blood above its specified limit. Whether driving was actually impaired does not come into it.

For THC, the Drug Driving (Specified Limits) Regulations 2014 set that limit at 2 microgrammes per litre of blood. That is one of the lowest figures in the whole table, alongside LSD at 1 and cocaine at 10. CBD does not appear anywhere in it.

So the law tests for the compound, not for the label on whatever was taken. A CBD product that complies with the one-milligram rule and one that does not are treated identically on the roadside: the question is only what the blood sample shows. Conviction carries a minimum one-year ban, an unlimited fine and up to six months in prison, according to the government's drug-driving guidance.

There is a medical defence, and it is tighter than people assume. Section 5A(3) covers a drug prescribed or supplied for a medical purpose and taken as directed, and only where the person's possession of it was lawful in the first place. Section 5A(4) removes the defence if the prescriber's advice on how long to wait before driving was ignored. A shop-bought CBD oil is not a prescription, and the defence does not reach it. If you are a patient with questions about your own prescription, that conversation belongs with the prescriber, not a blog.

What happened to the 50-microgram THC limit?

It was agreed and then not made law, which is the most useful single fact about where the CBD and THC line sits right now.

In December 2021 the Advisory Council on the Misuse of Drugs advised replacing the one-milligram-per-container test for consumer CBD products with a limit of 50 micrograms of each controlled cannabinoid per "unit of consumption", meaning the amount typically consumed on one occasion. The government's response, accepted on 24 October 2023, took that recommendation and said it intends to legislate, subject to Parliament. It added that the definition of a unit of consumption "will require further careful consideration".

Three years on, that consideration is still under way. The exempt product definition in regulation 2 of the Misuse of Drugs Regulations 2001, as published on legislation.gov.uk this month, still reads "more than one milligram of the controlled drug". The outstanding amendments listed against that regulation come from a 2025 order on pharmacy supervision and have nothing to do with CBD.

That matters for anyone reading confident claims about "the new THC limit". There isn't one in force. The two tests are different in kind, too: one milligram across a whole container against 50 micrograms per serving, and which is stricter depends on how many servings a bottle holds. At 50 micrograms a serving, a bottle reaches one milligram by its twentieth serving, so a small bottle would gain headroom under the new test and a large one would lose it. Accepted advice is not law until a statutory instrument says so, a gap we have seen before with the hemp licence threshold in hemp vs cannabis.

Does the CBD and THC split say anything about legalisation?

Not much, and it is worth being plain about why. CBD is legal because the 1971 Act never named it. Policy did not move. The THC side of the table, the side that covers cannabis itself, has not changed since the 2009 reclassification back to Class B, and the medical route opened in November 2018 is a prescription route through specialist doctors, not a consumer one.

Every change described above, the 50-microgram limit included, would tidy the rules for CBD. None of them touches THC, and none of them would bring a legal cannabis market closer. That would take an Act of Parliament with a government behind it, and nobody honest can give you a date for one. High in Hackney follows that change, the one Parliament has not started, rather than the adjustments at the edges of the CBD shelf.

High in Hackney is a waitlist for the day UK law changes for adults. Nothing is sold here and nothing can be until Parliament acts, but the people on the list hear first when it does. Join the waitlist