New 2025 SHRN data shows regular vaping and smoking have fallen among secondary school learners in Wales. We look at the latest figures, what they mean and why prevention work still matters.
Information / What’s in a vape?
What’s in a vape?
A legal nicotine vape sold in Great Britain usually contains a small number of main ingredients, but the device, liquid and aerosol are not all the same thing. Knowing the basics makes it easier to understand labels, spot unusual products and avoid myths.
Last reviewed: 25 September 2026
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Most legal e-liquids contain nicotine, propylene glycol, vegetable glycerine and flavourings.
Some e-liquids are nicotine-free. When the liquid is heated it forms an aerosol that is inhaled. It is often called “vapour”, but it is not simply water vapour.
The main ingredients
Nicotine
An addictive drug. Different products contain different strengths, and some e-liquids contain no nicotine.
Propylene glycol (PG)
A liquid commonly used to carry flavour and nicotine and help produce the aerosol.
Vegetable glycerine (VG)
A thicker liquid that helps create visible aerosol or “clouds”.
Flavourings
Ingredients used to create flavours. Legal nicotine vapes still have to comply with product rules on ingredients and notification.
What is actually inside the device?
E-liquid
The liquid mixture held in a pod, cartridge, tank or refill bottle.
Heating coil
A small heating element turns the liquid into an aerosol when the device is activated.
Battery
Powers the heating coil. Rechargeable devices should be used and charged according to the manufacturer’s instructions.
Is vape aerosol just water vapour?
No. Vapes create an aerosol from heated e-liquid. The aerosol can contain nicotine, flavouring chemicals and other substances formed or released during heating.
That does not make vaping equivalent to smoking. Legal vapes expose users to significantly fewer harmful substances than cigarettes, which burn tobacco and produce tar, carbon monoxide and thousands of chemicals. Vaping is still not risk-free.
What rules apply to legal nicotine vapes?
Under current Great Britain product rules, nicotine-containing vapes must be notified to the MHRA before sale. Rules include a maximum nicotine strength of 20 mg/ml, a maximum tank or pod capacity of 2 ml, and a maximum 10 ml nicotine refill container. Certain ingredients, including caffeine and taurine, are prohibited.
These rules help distinguish legal consumer products from products that do not meet UK requirements.
What about illegal or unusual vapes?
An illegal vape may exceed nicotine limits, contain prohibited ingredients or fail to appear on the MHRA notification list. Products sold as THC, CBD or cannabis vapes sit outside ordinary nicotine-vape assumptions and may contain unexpected substances, including synthetic cannabinoids.
THC & cannabis vapes
Why an illicit cannabis vape may contain something different from its label.
Spice & synthetic cannabinoids
What schools and families need to know about unexpected synthetic cannabinoids.
For schools and parents
You do not need to dismantle a device or investigate its contents yourself. Look at the packaging, nicotine strength, product name and where it came from. If a young person becomes unwell after using an unknown vape, deal with their health first and tell medical staff what you know.
Sources & further reading
ASH
Current UK evidence and key messages on vaping, relative harm and legal products.
NHS
How vapes work, typical e-liquid ingredients and their role in quitting smoking.
MHRA
Current Great Britain product requirements for nicotine-containing vapes and refill containers.