Why you vaporise it rather than smoke it

Is it legal to smoke prescribed cannabis in the UK?

No

In the UK, smoking a cannabis-based product for medicinal use is prohibited by regulation.

You vaporise your prescription instead. You do not roll it, smoke it or burn it.

The law

When cannabis-based products for medicinal use were rescheduled in November 2018, the regulations that made prescribing possible also placed a specific restriction on how the product may be taken.

Regulation 16A(3) of the Misuse of Drugs Regulations 2001, inserted by the 2018 amendment, states:

"A person shall not self-administer a cannabis-based product for medicinal use in humans by the smoking of the product (other than for research purposes in accordance with regulation 13)"

So the vaporiser is not an optional accessory. For a dried flower prescription it is the equipment the legal framework assumes you will use.

What that means in practice

Your prescription will specify how the product is to be taken. For dried flower that means vaporisation, which is why your clinic will have raised the subject of a device — and why the device is a separate purchase, since the regulations govern the medicine, not the hardware.

If you are unsure how your own prescription is meant to be taken, that is a question for your prescribing clinician or your pharmacy. It is written into what you have been prescribed, and it is not something we can answer for you.

So what is the actual difference?

The two are physically different processes.

Combustion is burning. Plant material reaches a temperature at which it ignites and breaks down, and that breakdown creates a large number of new compounds that were not present in the material beforehand — including smoke, ash and tar. This happens somewhere above 230°C, though it depends on the material and on how much air is reaching it.

Vaporisation is a change of state, not a chemical breakdown. The material is heated to a point where the active compounds within it evaporate — turn from a liquid or solid into a vapour — but the plant material itself is never taken to the temperature at which it burns. Nothing is set alight. What you inhale is the compounds that have evaporated, not the products of something burning.

That is why a dry herb vaporiser holds a set temperature, and why the useful range sits well below the point of combustion. Our temperature guide covers the ranges and where the ceiling is.

Why your device is built the way it is

Once you know the distinction, several things about a decent vaporiser stop looking like features and start looking like requirements.

Temperature control exists to keep the material below the point at which it would burn. A device that cannot hold a temperature cannot reliably do that.

Even heating matters because a device with hot spots can take part of the load past combustion while the rest is still below it — which is why a properly ground, evenly packed chamber is worth the trouble.

The vapour path — the route from chamber to mouthpiece — is made of glass and stainless steel in better devices, because those materials are stable at the temperatures involved.

If your device is producing something that smells like smoke, tastes acrid, or leaves black rather than brown residue, it has stopped vaporising and started burning. That usually means the temperature is set too high.

General information, not medical advice

As Prescribed sells equipment. We are not a pharmacy, a clinic or a prescriber, and nothing here is medical advice. This article is general information written for people who already hold a prescription — it is not tailored to you and takes no account of your condition, your other medicines or your circumstances.

Please read things for yourself: follow the manufacturer's instructions supplied with your device and the patient information supplied with your medication in preference to anything we have written. For anything about your medication, your dose or your condition, speak to your prescribing clinician or your dispensing pharmacy.

We set out what we know so you can weigh it up, check it against your own sources, and decide for yourself what suits you.