CBD vape juice: what is in the bottle

The carrier, and what the ratio does

Almost every vape juice is built on the same two liquids, in different proportions, and the ratio is usually printed as something like 70/30.

Carrier	What it contributes
Propylene glycol (PG)	Thin, carries flavour well, gives a sharper sensation in the throat. More of it suits small mouth-to-lung devices.
Vegetable glycerin (VG)	Thicker and sweeter, makes denser vapour, mutes flavour slightly. More of it suits higher-power devices.

Neither changes what the CBD does. The ratio is a comfort and hardware question, and a high-VG juice in a device built for thin liquid is the usual cause of a burnt taste.

Milligrams per millilitre

A bottle stating 1000 mg tells you nothing until you know the volume. A 30 ml bottle at 1000 mg is about 33 mg per millilitre; a 10 ml bottle at the same total is 100. Two products advertising the same headline number can be three times apart in strength.

What has been found in these bottles

Forensic chemists analysing commercially available CBD e-liquids reported, in Forensic Science International, products containing the synthetic cannabinoid 5F-ADB and, separately, dextromethorphan — neither declared on the label. A 2017 JAMA analysis of 84 CBD extracts found around seven in ten inaccurately labelled.

That is the reason the certificate matters more than the flavour list. A synthetic cannabinoid is not a strong CBD: compounds of that family act at the CB1 receptor far more powerfully than THC and have been linked to severe adverse events.

What a certificate should cover

• Cannabinoids, with a THC number rather than the phrase "THC free".
• Residual solvents from extraction.
• Heavy metals and pesticides.
• A date and a batch code matching the bottle you were sent.

Flavourings are not free

The flavour is the part of a vape juice with the least oversight and the most chemistry. Some flavouring compounds behave differently when heated than when eaten, which is a live research question rather than a settled one, and sweetened juices are also the ones that gunk a coil fastest.

Practical version: a plainer juice is easier on hardware, and an unflavoured one removes a variable if you are trying to work out what the CBD does.

The device matters as much

Setting	What it changes
Power	More vapour per puff and more thermal degradation. Research in the New England Journal of Medicine found formaldehyde-releasing compounds rising sharply with voltage.
Coil resistance	Matches the device to the carrier ratio. A thick juice needs a coil that can feed it.
Airflow	Tighter runs cooler and slower; wide open delivers more per second.

Mouth to lung, or direct to lung

The two ways people draw on a device change which juice suits them, and the shelf assumes you already know which you are.

• Mouth to lung is a cigarette-like draw into the mouth first, on tight airflow and a small device. It suits thinner, higher-PG juice.
• Direct to lung is a long open draw straight in, on a high-power device. It suits thicker, higher-VG juice and gets through a bottle far faster.

A juice that tastes harsh, or gives nothing at all, is usually a mismatch between these two rather than a bad bottle.

How long a bottle lasts

The arithmetic that makes this category comparable also tells you what you are buying. A 30 ml bottle at 1000 mg is about 33 mg per millilitre; if a tank holds 2 ml and you fill it twice a week, the bottle is roughly seven or eight weeks of use and about 66 mg a fill.

That matters because it puts inhaled CBD in proportion. A few puffs is a small number of milligrams, and the trials that found anything at all used doses in the hundreds, by mouth. Nothing follows from that about what a vape does or does not do — only that the two are not the same quantity of the same thing.

Nicotine, and the bottles beside these

CBD juice sits on a shelf with nicotine juice, in identical bottles, from some of the same brands. Two practical consequences follow.

• Read the label twice. Nicotine strength is printed the same way milligrams of CBD are, and 6 mg of one is not 6 mg of the other.
• Keep them apart at home, particularly from anyone who cannot read the difference.
• A CBD juice is not a way to stop nicotine. Nothing in it acts on the receptors nicotine acts on, and no trial supports it for that. Licensed stop-smoking support does.

Storage, and how long a bottle keeps

Vape juice does not spoil in the way food does, but it does change, and three things drive it.

What to avoid	What it does
Light	Ultraviolet degrades cannabinoids. Amber glass exists for this reason, and a clear bottle on a windowsill is the worst case.
Heat	Speeds every degradation reaction, and thins the liquid enough to flood a coil.
Air	Oxidation dulls flavour first and cannabinoid content later. A part-used bottle left open loses both.

Cool, dark, closed, upright. On that footing a bottle is good for a year or so; past that, expect the flavour to have flattened before anything else has.

What a coil costs you

The consumable in a refillable setup is the coil, and its condition changes the product more than most people credit.

• A new coil delivers more per puff than the same coil a fortnight later, which is a variable if you are trying to judge a dose.
• Sweetened juices shorten coil life sharply; sugars caramelise on the wire.
• Prime a new coil — wet the wick and wait a few minutes — or the first puff is a burnt one.
• A burnt taste is never the juice. It is dry wick, and pulling harder makes it worse.

Never the tincture

Why this page names no products

It listed four. Their links had drifted from the brands they named — the legacy page carried stale affiliate URLs under headings rewritten later — and a link that sends a reader to a different brand than the one they clicked is worse than no link at all.

The arithmetic and the certificate checks above do not go out of date, which is more than can be said for a 2019 shortlist.