Why is vaporising used instead of smoking?

This is one of the few places in this field where the evidence points clearly in one direction. Burning anything and inhaling the smoke is harmful, the harm is avoidable, and avoiding it changes nothing about the therapeutic effect.

What actually differs

Burning plant material at high temperature breaks compounds down and creates new ones. Vaporising heats it enough to release the active compounds as a vapour without reaching combustion.

The distinction is temperature. Combustion — a flame, a glowing tip — reaches several hundred degrees and destroys part of what you are trying to inhale while generating smoke. A vaporiser holds the material at a lower, controlled temperature, high enough to turn the active compounds into a vapour but below the point where the plant catches and burns. What you breathe in is vapour rather than smoke, and that difference is the whole argument.

The products of combustion — tar, carbon monoxide, polycyclic aromatic hydrocarbons and other irritants — are the same class of substances that cause harm in tobacco smoking. They contribute nothing to the therapeutic effect. Avoiding them costs nothing clinically, because the active compounds you are trying to deliver come off well below the temperature at which the plant material actually burns. In other words, burning is not necessary to get the medicine into you; it only adds harm.

Vaporising also gives more consistent delivery, which matters when the aim is to find a reproducible dose rather than an effect. Combustion is chaotic: temperature spikes, some of the active compounds are destroyed by the heat, and what reaches you varies from one draw to the next. Heating below the point of combustion is more controlled, so the same preparation behaves more predictably each time, which is exactly what a treatment being carefully titrated needs.

What vaporising does not fix

It reduces one category of harm. It does not make inhalation harmless and it does not change anything about the cannabinoids themselves.

• Airway irritation, cough and throat discomfort are still common
• Long-term effects of habitual vapour inhalation are not fully characterised
• People with asthma or COPD may find any inhaled route unsuitable
• The cannabinoid risks are unchanged — impairment, anxiety, cardiovascular effects
• Device temperature and maintenance matter, and running too hot approaches combustion

The honest position is that vaporising is a harm-reduction step within inhalation, not a clean bill of health for it. It removes a large and well-understood category of harm; it leaves the rest. For that reason an inhaled route is not automatically the right choice, and it is weighed against the alternatives for each person.

Where an inhaled route does not suit, other routes are available and are covered in What forms do cannabis-based medicines come in?

The tobacco question

Mixing cannabis with tobacco remains common in the UK and is worth raising explicitly, because it changes the risk picture substantially.

It introduces nicotine dependence, which makes stopping harder, and adds the cardiovascular and cancer risks of tobacco smoking. Someone who has been using illicit cannabis this way and moves to a prescribed vaporised route is making a meaningful reduction in harm — both by removing combustion and by removing the tobacco. It is worth naming that this is often the single biggest health change a new patient makes, and it is a reason to be candid about existing habits rather than to gloss over them.

Prescribers ask about this. Answer honestly — the point is to get the treatment right, and a history of tobacco use changes the advice you should be given.

If you want to stop smoking, NHS stop smoking services are free and are more effective than going it alone.

Using a vaporiser sensibly

Where an inhaled route is prescribed, dried flower is heated in a vaporiser rather than burned. Getting reliable results from it depends on a few practical habits, all of which sit under the guidance your clinic and pharmacy give for your specific device and preparation. Treat the points below as general orientation rather than instructions for a particular product.

• Temperature. The point of vaporising is to stay below combustion. Running a device too hot moves it back towards burning, which reintroduces the very by-products vaporising is meant to avoid.
• Technique. How you draw and how long you hold affects how much is absorbed. A gentler, steadier approach is usually easier on the airway than a hard, fast draw.
• Maintenance. Devices need cleaning to work consistently and hygienically. A neglected device delivers less predictably, can taste unpleasant, and is harder to keep at a steady temperature.
• Storage. Dried flower is a medicine and a controlled drug; keep it in its labelled pharmacy packaging, secured from others, as covered in how medical cannabis is dispensed and delivered.

Because an inhaled dose acts within minutes, it is easier to titrate by feel than a swallowed preparation — but that also makes it easier to take more than intended. Follow the amount and schedule your prescriber has set rather than adjusting by how you feel in the moment, and give each dose time to settle before deciding anything about the next.

Vaporising within the wider treatment

Vaporising is one route among several, chosen on clinical grounds rather than preference. It is fast-acting and wears off within a few hours, which suits some patterns of symptoms and not others.

Many people who use an inhaled route also use something longer-acting as a background, with the faster inhaled dose reserved for breakthrough symptoms. That combination, and how the routes compare, is set out in how cannabis-based medicines are taken, and how any dose is built up in how a dose is decided and adjusted.

Switching to vaporising removes the harms of combustion, but it does not remove the effects of the cannabinoids themselves. Impairment, anxiety, dizziness and the other effects covered in side effects of cannabis-based medicines apply to any route. Whether an inhaled medicine is appropriate for you at all is an individual decision made by a specialist, and for some people — particularly those with significant respiratory disease — it will not be.

Questions worth asking your specialist

If an inhaled route is being considered, a few questions help you use it safely and know what to expect:

• Is an inhaled route suitable for me given my chest and general health?
• What temperature range should I be using, and why?
• How quickly should it act, and how long should each dose last?
• How do I avoid taking more than intended when the effect comes on fast?
• Should I combine it with a longer-acting preparation, and how would they fit together?

Honest answers about any current tobacco or cannabis use will make this advice more useful, not less — the aim is to get the treatment right. Nothing you say about past or current use changes your eligibility to be assessed fairly, and it often changes the advice for the better.

Patient guide · Written by the Flora House editorial team · Last reviewed: 7 October 2026