Vaping Juice Ingredients: What's Actually In E-Liquid?

One of the most common questions new vapers ask is: "What exactly am I inhaling?" It's a fair question, and the honest answer is straightforward — UK-legal e-liquids have a short, well-understood ingredient list. There's no mystery, and there's no need to worry about what you can't pronounce.

This guide explains every ingredient in plain English, covers what's banned under UK regulations, and puts to rest some persistent myths you may have read online.

The 4 Core Ingredients

Every UK-compliant e-liquid is made from the same four ingredient types. That's it — four. Let's look at each one in turn.

Ingredient	Abbreviation	Role in E-Liquid	Common Uses Outside Vaping
Propylene Glycol	PG	Carrier liquid, throat hit, flavour carrier	Food additives, medical inhalers, cosmetics
Vegetable Glycerin	VG	Carrier liquid, vapour production, sweetness	Food sweetener, soap, pharmaceuticals
Nicotine	—	Nicotine delivery (optional)	NRT products (patches, gum, inhalers)
Flavourings	—	Taste and aroma	Food and confectionery

Propylene Glycol (PG)

Propylene glycol is a colourless, almost odourless liquid with a slightly sweet taste. It's one of the most widely used food-safe substances in the world, found in everything from cake mixes to injectable medicines.

In e-liquid, PG serves two key functions:

• Flavour carrier — PG is very efficient at holding and releasing flavour molecules. High-PG liquids tend to taste more intense than high-VG versions of the same flavour.
• Throat hit — PG produces the "scratch" at the back of the throat that many ex-smokers associate with a satisfying vape. This is why beginner liquids and nic salts tend to have more PG.

PG is thinner than VG, which makes it compatible with a wider range of coils and devices. Starter kits and pod devices work well with 50/50 or higher-PG liquids.

A small proportion of people have a sensitivity to PG, which can cause a dry or irritated throat. If you experience this, try a higher-VG liquid — many vapers move to 70VG/30PG or even max VG once they've been vaping for a while.

Vegetable Glycerin (VG)

Vegetable glycerin is a plant-derived liquid extracted most commonly from palm, soya, or coconut oil. It's thick, slightly sweet, and completely odourless. Like PG, it has an excellent safety record and appears in hundreds of food and pharmaceutical products.

In e-liquid, VG does the heavy lifting on vapour production:

• Cloud production — VG is responsible for the thick, visible vapour you see when someone vapes. The higher the VG ratio, the more cloud a liquid produces.
• Smoothness — VG produces a notably smoother inhale than PG. High-VG liquids (70VG+) are much gentler on the throat, which is why sub-ohm vapers and cloud chasers favour them.
• Subtle sweetness — VG has a very mild natural sweetness that contributes to the overall flavour profile of a liquid.

The main downside of high-VG liquid is its thickness. Thin coils and wicks in beginner devices can struggle with very viscous liquids, which is why shortfills (typically 70VG/30PG) are recommended for sub-ohm tanks with larger coils rather than basic starter pens.

Nicotine

Nicotine is extracted from tobacco plants and purified for use in e-liquids. It's the same nicotine found in cigarettes, patches, and nicotine gum — a stimulant that creates the satisfying sensation smokers are familiar with.

Freebase Nicotine

Traditional e-liquids use freebase nicotine — the standard form that vaporises readily at lower temperatures. Freebase nicotine is slightly alkaline, which creates the throat hit you feel at higher strengths. UK regulations cap freebase nicotine in 10ml bottles at 20mg/ml.

Nicotine Salts

Nicotine salts (nic salts) are created by combining nicotine with an organic acid — most commonly benzoic acid. The result is a nicotine form that is less alkaline, smoother to inhale even at 20mg, and absorbed by the body more rapidly. This is why nic salt liquids feel more satisfying at the same strength as freebase — and why they're the preferred format for ex-smokers and pod kit users.

The UK 20mg Legal Limit

Under TRPR, e-liquids with nicotine can only be sold in bottles up to 10ml, and the nicotine strength cannot exceed 20mg/ml. This applies to both freebase and salt nicotine. Shortfill liquids — 50ml bottles — must be nicotine-free (0mg) at the point of sale, with room left to add a separate nic shot.

Flavourings

E-liquid flavourings are food-grade concentrates — the same category of ingredients used in confectionery, drinks, and baked goods. They're what gives a liquid its strawberry, bubblegum, or tobacco character.

Flavourings are typically a small percentage of the total liquid — often 5–15% — but they have an outsized impact on the overall experience. The quality and source of flavourings is one of the main factors that separates a great e-liquid from a mediocre one.

What's Allowed

Food-grade flavouring compounds that have been assessed as safe for inhalation are permitted. Reputable UK brands use flavourings that have been cleared specifically for use in e-liquid, not just for oral consumption (since the safety profile of inhaled substances can differ from ingested ones).

What's Banned

UK regulations specifically prohibit certain flavouring ingredients in e-liquid. See the next section for the full list.

What's NOT In UK E-Liquid

There's a lot of misinformation online about e-liquid ingredients. Here's what UK-compliant e-liquid does not contain — and why some of the scarier claims you may have read are inaccurate.

Banned Ingredients Under TRPR

• Diacetyl — a butter-flavoured compound linked to a serious lung condition called "popcorn lung." Banned in UK e-liquid. Reputable brands have never used it.
• Acetyl Propionyl — a similar compound with comparable risks. Also banned.
• Artificial colourings — e-liquid cannot be coloured to make it look more attractive.
• Caffeine and taurine — stimulant additives are prohibited.
• Vitamins and minerals — health-claim additives are not permitted in nicotine-containing liquids.

Common Myths Debunked

How to Read an E-Liquid Label

Every TPD-compliant e-liquid sold in the UK must display specific information on its label. Here's what to look for:

• Nicotine strength — displayed in mg/ml (e.g. 3mg, 6mg, 12mg, 20mg) or as a percentage (e.g. 0.3%, 0.6%, 2%).
• VG/PG ratio — shown as a percentage split, e.g. 70VG/30PG or 50/50. This tells you which devices the liquid is suited to.
• Volume — UK law restricts nicotine-containing liquids to 10ml bottles. Shortfills (nicotine-free) can be up to 50ml.
• Batch number and MHRA registration — all notified e-liquids have been registered with the Medicines and Healthcare products Regulatory Agency.
• Age restriction warning — all nicotine-containing products must display the 18+ warning.
• Ingredients list — required by law. Should list PG, VG, nicotine (if applicable), and flavouring components.

Frequently Asked Questions

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