What is in a vape is two questions. The bottle usually holds nicotine, propylene glycol and flavourings, says the American Lung Association. The aerosol adds chemicals formed by heating and, a 2018 Johns Hopkins-led study found, metals such as nickel and lead from the coil.

Evergreen: this desk read these sources on 15 October 2026.

What is in a vape once it is heated?

Heating forms more toxic chemicals, says the ALA, whose list names formaldehyde and acrolein. Olmedo and colleagues sampled 56 users’ devices: median nickel was 2.03 µg/kg in the refill bottle, 233 in the tank and 68.4 in the aerosol. One study, not a market survey.

What does the law ban?

MHRA guidance, last updated 16 August 2024, caps UK tanks at 2ml, nicotine refills at 10ml and strength at 20mg/ml, and bans “certain ingredients including colourings, caffeine and taurine”. For the US, the ALA says FDA has not “issued any standards on the products”.

FAQ

What’s in vape juice?

Usually nicotine, propylene glycol and flavourings, per the American Lung Association; campaign explainers such as New Zealand’s Don’t Get Sucked In add vegetable glycerin and sweeteners. Nicotine-free is not guaranteed: the CDC says some “zero percent nicotine” products were found to contain it.

What happens when vape juice is heated?

It becomes an aerosol, not harmless water vapour, says the CDC. The American Lung Association says more toxic chemicals form as the liquid heats, and in the 2018 study, tank and aerosol samples held far more nickel and lead than refill bottles.

Why do vapes have flavours?

Flavour sells the bottle, but the CDC makes the point that matters: some flavourings safe to eat may not be safe to inhale, because the lungs process substances differently from the gut. Its named example is diacetyl, linked to serious lung disease.

Related: strength maths, sweeteners, and a Korean test of “nicotine-free” vapes. Whatever the label, a vape can deliver nicotine, an addictive drug; nothing here is a reason to start.