At a Glance
- In the UK, prescribed cannabis flower should not be smoked. It is intended to be taken with a medical vaporiser, in line with your prescription.
- Under the Misuse of Drugs Regulations 2001, a person must not self-administer a cannabis-based medicine by smoking it.
- A vaporizer works by heating cannabis to a controlled temperature, usually between about 160°C and 210°C. This releases the active compounds as a vapour without burning the plant.
- Vaporising is a preferred method as burning cannabis creates smoke that contains carbon monoxide, tar and other harmful substances. Vaporising produces far less of these by-products.
- Vaporising is generally considered lower-risk than smoking, but it is not risk-free, and research into its long-term effects is still developing.
- Medical vaporisers are regulated medical devices designed for accurate, consistent temperature control. Consumer vapes from the high street are not a substitute.
If you’ve been prescribed medical cannabis flower, it is recommended you take it with a medically approved vaporiser. Although cannabis is often associated with smoking, we strongly advise against smoking your medicine because of the health risks.
Unlike smoking, vaporisation heats the cannabis flower without burning it, releasing the active compounds while reducing the exposure to many of the harmful chemicals and carcinogens found in smoke.
This blog explains why smoking medical cannabis is discouraged, how vaporisation of cannabis works, and what makes medical-grade vaporisers different from products found on the high street.
Why Is Medical Cannabis Vaporised Instead of Smoked?
Medical cannabis flower is vaporised rather than smoked for two main reasons: the law does not permit it to be self-administered by smoking, and vaporising avoids many of the harmful substances created when plant material is burned.
In the UK, prescribing is governed by the Misuse of Drugs Regulations 2001 (as amended in 2018). Regulation 16A states that a person “shall not self-administer a cannabis-based product for medicinal use in humans by the smoking of the product”, other than for approved research. Taking your medicine with a vaporiser keeps you within the terms of your prescription and the law.
There is also a clinical reason. Like any medicine, medical cannabis is prescribed and monitored, and the way it is taken is chosen to balance how well it works with your safety. Vaporising allows the active compounds to be delivered while reducing exposure to the by-products of burning.
What is the difference between smoking and vaporising?
The key difference is heat. Smoking burns the plant, while vaporising warms it to a controlled temperature that is high enough to release the active compounds but not hot enough to set it alight.
What happens when cannabis is smoked?
Burning cannabis, known as combustion, creates smoke. Alongside the active compounds, that smoke contains a mixture of substances that can be harmful to breathe in. It can also destroy some of the active compounds before they are inhaled.
Cannabis smoke can contain:
- Carbon monoxide: a toxic gas that reduces how well the blood carries oxygen.
- Other potentially harmful compounds: substances that can irritate the airways and, over time, damage lung tissue or cause cancer.
Regular exposure to any smoke may also contribute to symptoms such as coughing, wheezing and bringing up more phlegm.
How does vaporisation work?
A vaporiser heats cannabis flower or extract to a controlled temperature, typically between about 160°C and 210°C. This is warm enough to release the active compounds, including THC (tetrahydrocannabinol) and CBD (cannabidiol), along with the plant’s aromatic compounds called terpenes, as a vapour. Because the plant does not burn, you breathe in vapour rather than smoke.
Medical vaporisers are designed to hold a steady, accurate temperature. This helps deliver the medicine more consistently from one use to the next, provided the device is used according to the manufacturer’s instructions and your clinician’s advice. Many consumer vaporisers are not built to the same standard.
What does the research say about vaporising compared with smoking?
Research to date suggests that vaporising cannabis exposes the lungs to fewer of the harmful by-products of burning, and can deliver the active compounds in a measurable, consistent way. The studies are mostly small and early, so the findings below are best read as encouraging signals rather than proof. None of these studies establishes that cannabis treats any particular condition.
Less carbon monoxide than smoking
A pilot study by Abrams and colleagues (2007) compared vaporising cannabis, using a Volcano device, with smoking it. Peak THC levels in the blood were similar for both methods, but carbon monoxide levels rose substantially after smoking and barely changed after vaporising. A later review by Loflin and Earleywine (2015) reached a similar conclusion: switching from smoking to vaporising is associated with fewer self-reported respiratory symptoms. According to PubMed, both are published, peer-reviewed studies.
Consistent delivery of the active compound
Because vaporising does not lose compounds to burning and side-smoke, it can be an efficient way of delivering them. In an early study by Eisenberg and colleagues (2014), a metered-dose cannabis inhaler, a research device that is different from the vaporisers prescribed in the UK, produced a consistent level of THC in the blood with little variation between the eight participants. Findings like these are why researchers are interested in inhaled delivery, though they come from small, early studies and do not tell us how any individual will respond.
What types of medical cannabis vaporiser are there?
Medical cannabis may be prescribed for inhalation in different formats, including dried flower and, where clinically appropriate, pre-filled vape cartridges. Each format requires a compatible device.
Dry Herb Vaporisers
Dry herb vaporisers are designed specifically for use with dried cannabis flower. The flower is ground before being placed into the device’s heating chamber, where it is heated to release cannabinoids and terpenes without burning the plant material.
When they may be considered: Dried cannabis flower may be prescribed when an inhaled formulation with a relatively rapid onset of action is clinically appropriate.
Vape Cartridges (Liquid Extracts)
Pre-filled vape cartridges contain a medical cannabis extract and are used with a compatible device. They require little preparation before use.
When they may be considered: Like dried flower, vape cartridges provide an inhaled form of medical cannabis with a relatively rapid onset of action. The key difference is that they require less preparation before use.
Which vaporisers are approved for medical use in the UK?
n the UK, the medical dry herb vaporisers used for prescribed cannabis are regulated medical devices manufactured by Storz & Bickel. At the time of writing these include a desktop device (the Volcano Medic range) and a portable device (the Mighty+ Medic). For vape cartridges, the QMID device is the only one to receive CE registration in the UK at present. Being certified as a medical device means a vaporiser has been assessed for safety, temperature accuracy and the materials used in its construction.
Certification applies to the device, not to any medicine used with it. A certified vaporiser lowers the risks linked to burning, but it does not remove the risks of inhaling active cannabinoids. To use one safely, keep within the temperature range your clinician recommends, and follow the manufacturer’s guidance on regular cleaning and maintenance. Your clinical team can advise on obtaining a suitable device.
Frequently asked questions
Can you smoke medical cannabis in the UK?
No. Prescribed cannabis flower is not intended to be smoked, and the Misuse of Drugs Regulations 2001 state that a person must not self-administer a cannabis-based medicine by smoking it. It is intended to be taken with a medical vaporiser, in line with your prescription.
Is vaping medical cannabis better than smoking it?
Vaporising is generally considered lower-risk than smoking, because heating the plant without burning it produces far less carbon monoxide and other harmful by-products. Lower-risk does not mean risk-free, and the long-term effects are still being studied.
What temperature should a cannabis vaporiser be set to?
Medical vaporisers usually operate between about 160°C and 210°C. The right setting for you depends on your device and your prescription, so follow the temperature range your prescribing clinician recommends and the manufacturer’s instructions.
CH3: Can I use a high-street vape or e-cigarette for my prescription?
Consumer vapes and e-cigarettes are not designed for prescribed medical cannabis and are not a substitute for a medical vaporiser. Speak to your clinical team about which device is appropriate for your prescription.
Does vaporising remove all the risks?
No. Vaporising reduces exposure to the harmful by-products of burning, but it still involves inhaling active compounds, and it does not remove any contaminants already present in the plant. Using medical cannabis supplied through regulated channels, and following your prescription, helps manage these risks.
[1] Loflin, M. and Earleywine, M. (2015). No smoke, no fire: What the initial literature suggests regarding vapourized cannabis and respiratory risk. Canadian Journal of Respiratory Therapy: CJRT = Revue Canadienne de la Thérapie Respiratoire : RCTR, [online] 51(1), p.7. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC4456813/.
[2] Abrams, D.I., Vizoso, H.P., Shade, S.B., Jay, C., Kelly, M.E. and Benowitz, N.L. (2007). Vaporization as a Smokeless Cannabis Delivery System: A Pilot Study. Clinical Pharmacology & Therapeutics, 82(5), pp.572–578. doi:https://doi.org/10.1038/sj.clpt.6100200.
[3] Eisenberg, E., Ogintz, M. and Almog, S. (2014). The Pharmacokinetics, Efficacy, Safety, and Ease of Use of a Novel Portable Metered-Dose Cannabis Inhaler in Patients With Chronic Neuropathic Pain: A Phase 1a Study. Journal of Pain & Palliative Care Pharmacotherapy, 28(3), pp.216–225. doi:https://doi.org/10.3109/15360288.2014.941130.
