CBD e-liquid: choosing your hardware, coil and wattage

A bottle's label states a quantity of CBD for a volume, and our article on dosing in mg/ml explains how to read it. The label does not say how much of that liquid leaves as aerosol with each puff.

Measurements published in Chemical Research in Toxicology in 2023 put figures on that relationship. On the same device, a 0.6 ohm coil produces 13.2 milligrams of aerosol per puff, 0.8 ohm produces 12.3 and 1.2 ohm only 7.4. On a more powerful build at 0.12 ohm, the value rises to 21.5 milligrams. The authors note an inverse relationship between the resistance value and the coil temperature, itself proportional to the mass of aerosol formed.

The consequence is direct: at an identical concentration, moving from a 1.2 ohm coil to a sub-ohm build mechanically multiplies the quantity of cannabidiol inhaled per puff.

Two families of hardware coexist, and they do not mix.

So-called conventional coils, from 1.5 to 1.8 ohm, work in a range of 4 to 20 watts. Low-resistance coils, around 0.5 ohm, operate between 15 and 100 watts. The term sub-ohm designates coils below 1 ohm, fitted to devices capable of 40 to 300 watts, where conventional hardware works under 10 watts.

An experiment run on thirty-two experienced vapers illustrates the gap in consumption. Over an hour of free use, the 0.5 ohm build at 40.5 watts used up to 1.00 millilitre of liquid, against 0.30 millilitre for the 1.5 ohm build at 13.5 watts, more than triple. For an e-liquid dosed at several hundred milligrams of CBD per bottle, the difference in cost and dose is anything but theoretical.

CBD e-liquids are formulated for the first family, a choice made for consistency with these measurements.

The inhalation style doubles that effect. A puff taken by indirect inhalation, where the vapour is first held in the mouth, represents a volume of about 55 millilitres over two to four seconds, with an airflow of 18.3 millilitres per second. A puff taken by direct inhalation, where the vapour goes straight to the lungs, represents 500 millilitres over three seconds, at 166.7 millilitres per second, according to measurements published in 2019.

Nine times the volume per puff, on hardware that already vaporises three times more liquid: indirect inhalation on a conventional coil remains the format suited to a cannabidiol e-liquid.

Propylene glycol and vegetable glycerine do not behave the same way. A crossover trial in thirty vapers, run on a 1.5 ohm coil at 7.3 watts, compared four ratios. The liquid made entirely of propylene glycol delivered the highest plasma concentration, 13.40 ng/mL, against 8.58 to 9.59 ng/mL for the glycerine-dominated liquids. In exchange, participants judged the 100 % propylene glycol markedly less pleasant and harsher on the throat. They also lengthened their puffs on the liquid richest in glycerine, a classic compensation behaviour.

The principle matters more than any set figure: glycerine, more viscous and less volatile, produces a denser aerosol but feeds a fine wick less well. Propylene glycol delivers more at low power, at the cost of comfort. Precise ratios are a matter of preference, and no standard fixes them.

An e-liquid contains neither vegetable oil nor fractionated coconut oil. It is made up of propylene glycol, glycerine, flavourings and the active ingredient, never a fatty substance.

The reason is documented. The American epidemic of vaping-associated lung injury totalled 2 807 hospitalisations or deaths as at 18 February 2020, including 68 deaths. The agent responsible was identified: vitamin E acetate was found in the bronchoalveolar lavage fluid of 48 patients out of 51, and in none of the 99 control participants. Work published in 2021 also shows that a fractionated coconut oil heated to 215 °C in a vaping device releases nine of its eleven constituents into the aerosol. It is therefore inhaled as intact triglycerides. That oil was not implicated in the epidemic, but it has no business in a lung.

Our article on the composition of CBD e-liquids sets out the additives to watch.

A lot of content gets this point wrong. The well-known limits, 20 mg/ml of nicotine, a 2 millilitre tank, a 10 millilitre bottle, are set by the order of 19 May 2016 on vaping products containing nicotine. As the title indicates, they belong to the section of the public health code devoted to products containing nicotine. A CBD e-liquid without nicotine is not subject to them, and a 30 millilitre bottle is lawful.

The ban on disposable devices, on the other hand, does apply to CBD puff bars. Law no. 2025-175 of 24 February 2025 inserted an article L. 3513-5-1 into the public health code. That article sits among the provisions common to all vaping products and covers pre-filled non-rechargeable devices, with no distinction as to the presence of nicotine. The ban has applied since 26 February 2025, with a fine of up to 100 000 €, raised to 200 000 € for a repeat offence. Our dedicated article returns to the ban on puff bars.

A study published in Scientific Reports in 2022 followed a CBD e-liquid over twenty-nine days in four conditions. Cannabidiol stayed relatively stable at 4 °C in the dark, but multiple degradation products appeared at room temperature and above, mainly cannabielsoin and CBD quinone. An opened bottle is therefore kept cool and away from light, like flowers. Our batch analyses are published before purchase, and heating steps are set out in our guide to vaporisation temperatures.