Dried flower or oil cartridge

Understanding the two main formats of a UK medical cannabis prescription

When patients receive a cannabis-based prescription for medicinal use in the UK, one of the first practical decisions they face is understanding what, exactly, they've been given. The two most common prescription formats — dried flower and oil in cartridge form — look quite different, work quite differently, and require entirely different equipment.

Dried cannabis flower

Dried cannabis flower is the plant's flowering material, harvested, dried and prepared to a pharmaceutical standard. In the UK, it is dispensed by weight — typically in sealed, tamper-evident containers — and supplied by specialist pharmacies working with licensed importers.

To use dried flower as part of a medical prescription, patients use a dry herb vaporiser: a device that heats the material to a controlled temperature, causing the active compounds to become a vapour that is inhaled. Crucially, the material does not burn. Vaporisation at the correct temperature avoids combustion and the harmful byproducts that come with it — one of the key reasons it is the medically recommended method.

Dried flower prescriptions offer a relatively quick onset of effect — typically within minutes — which makes them useful for conditions where rapid relief is relevant. The effect's duration and intensity depend on the specific product, the temperature used, and individual patient factors, which is why clinical guidance matters.

Oil in cartridge form

Cannabis oil prescriptions come pre-prepared: the oil is already inside a small sealed cartridge, ready to use. The cartridge connects to a battery using a standard 510-thread connection — the same standard used across the vaping industry, which means any quality 510-thread battery will work.

When you draw on a 510-thread device, the battery heats the oil in the cartridge to a temperature that causes it to vaporise. The effect is immediate and the process is simple, which makes oil cartridges a popular format for patients who prefer a more straightforward experience or who find the preparation involved with dried flower inconvenient.

Because the oil is pre-prepared, there's less variation in the setup compared to flower. The main variables for patients are the specific product they've been prescribed and the voltage setting on their battery, which affects how the oil is heated.

Which format is better?

Neither is universally better — they suit different patients and different conditions. Dried flower tends to offer more flexibility in terms of temperature and therefore the profile of active compounds you're accessing. Oil cartridges tend to be more convenient and more discreet.

Many patients, over time, are prescribed both. Your prescribing clinician will advise on format based on your specific condition, your lifestyle, and your response to treatment. If you have a preference — for convenience, for speed of onset, for discretion — it's worth raising with your clinic, as they can often tailor prescriptions accordingly.

What this means for equipment

The practical implication is straightforward: if your prescription is for dried flower, you need a dry herb vaporiser. If it's for oil in cartridge form, you need a 510-thread battery. If you're prescribed both formats, you need both types of device.

Our starter kit guide on the As Prescribed website matches kit recommendations to prescription format, so if you're not sure where to begin, that's a good starting point.

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.