What Is in a Vape?

What is in a vape?

A vape is really two things working together, the device and the e-liquid it heats. The device is a battery powering a coil and wick, while UK e-liquid contains just four ingredients, propylene glycol, vegetable glycerine, flavourings and nicotine. There is no smoke and no burning tobacco.

It helps to take the parts in turn. The hardware heats the liquid into an inhalable vapour, while the liquid is a simple, tightly regulated mix. This page explains the device components, the four e-liquid ingredients, what UK law bans and how it differs from a cigarette, so you know exactly what you are inhaling. As with any vape, this is for adults aged eighteen and over.

Let us look at the device, the four ingredients, the rules and the comparison.

People often imagine a long list of mystery chemicals, when the reality is far shorter. Knowing the actual contents tends to make the whole thing feel a lot less daunting.

The device and how it works

The hardware is straightforward. A battery powers a coil, the coil heats a wick soaked in e-liquid, then that turns the liquid into the vapour you inhale, with no flame and no combustion involved.

• Battery: rechargeable in reusable kits, built in on disposables.
• Coil: the heating element that warms the liquid.
• Wick: cotton that holds e-liquid against the coil.
• Tank or pod: the reservoir that stores the e-liquid.

The key difference from smoking is the heat. A vape gently warms the liquid into vapour rather than burning anything, so there is no smoke, no ash and none of the tar produced when tobacco is set alight, which is central to why it differs from a cigarette.

That single change, heating instead of burning, is the reason the two are so different to inhale. Everything else about a vape follows from that one principle.

The four e-liquid ingredients

UK e-liquid is simpler than many people expect. It contains only four ingredients, propylene glycol and vegetable glycerine as the base, plus flavourings and an optional dose of nicotine, all blended in carefully controlled amounts.

First, propylene glycol, known as PG, is a thin, clear carrier that delivers flavour and gives the throat hit, plus the same ingredient is found in asthma inhalers, food and stage fog machines. Second, vegetable glycerine, known as VG, is a thicker, slightly sweet liquid that produces the vapour clouds and smooths the hit. A 50/50 blend suits beginner pod kits, while high-VG liquid suits sub-ohm devices. Third, flavourings are food-grade and use sweeteners such as sucralose rather than sugar, since sugar would burn on the coil. Fourth, nicotine is optional and pharmaceutical grade, capped at 20mg per ml in the UK, available as harsher freebase or smoother nic salt, with 0mg options for those who want none. That really is the whole recipe.

There are no hidden extras beyond those four, since UK rules simply do not permit them. What varies between bottles is the ratio, the flavour and the nicotine level, not the core ingredients.

The rules and how it compares

What goes into a UK vape is tightly controlled. Every e-liquid sold in the UK is MHRA-notified and tested for compliance, so only those four ingredients are allowed and substances like certain colourings or stimulants are banned.

On the rules, UK law means each e-liquid is checked before it can be sold, nicotine is capped at 20mg per ml and must be pharmaceutical grade, plus a list of ingredients is banned from e-liquid. This is why buying from reputable UK retailers matters, since unregulated imports may not meet these standards. On the comparison, a cigarette burns tobacco and produces smoke, tar and thousands of chemicals, many of them harmful, whereas a vape heats a simple four-ingredient liquid without combustion. That is why health bodies say vaping is far less harmful than smoking, though it is not risk free and is only for adult smokers looking to switch and existing adult vapers. If you have never smoked, you should not start vaping, since it is intended only as a switch for smokers.

• Tested first: UK e-liquids are MHRA-notified before sale.
• Capped nicotine: 20mg per ml maximum, pharmaceutical grade.
• Banned extras: certain colourings and additives are not allowed.
• No combustion: vapour, not smoke, tar or ash.

If you want to dig deeper, see our explainer on what nicotine is. It pairs well with our guide on what vaping is and our look at what nicotine salt is.

For the full set of guides, the vaping FAQs hub brings everything together in one place.

Frequently asked questions