Is diacetyl still in vape juice? Test data and the UK list
Is diacetyl still in vape juice? A Harvard-led test found it in 39 of 51 flavours. What that 2015 data shows, and what UK guidance says not to include.
Is diacetyl still in vape juice? Nobody has published a current market-wide answer in what this desk read. The test this desk read, a Harvard-led study of 51 flavoured e-cigarettes, received by its journal in May 2015, found diacetyl in 39 of them. In Great Britain, MHRA guidance now lists it among substances that should not be included in e-liquids.
Evergreen: this desk read the Allen paper, the MHRA ingredient guidance and an Australian regulator’s evaluation on 24 October 2026. Nothing here was tested by this desk; every figure is the researchers’ or the regulator’s.
Is there diacetyl in vapes? What the 51-flavour test found
Allen and colleagues (Environmental Health Perspectives, received May 2015, issue June 2016) discharged each product fully and analysed the air stream under OSHA method 1012. At least one of the three buttery-flavour compounds turned up in 47 of 51 flavours.
| Compound | Detected in (of 51) | Maximum, µg per e-cigarette |
|---|---|---|
| Diacetyl | 39 | 239 |
| 2,3-pentanedione | 23 | 64 |
| Acetoin | 46 | 529 |
The hits were not only in custards and candy. The authors note detections in flavours sold as “classic” and menthol, which is worth remembering before you assume a tobacco bottle is clean.
Does diacetyl-free mean diketone-free?
No. Diacetyl and 2,3-pentanedione turned up together in 21 flavours, and the authors read that as 2,3-pentanedione often being used alongside diacetyl, not only as a replacement. A label promising one is absent tells you nothing about the other. That matters most in the cream and custard family; our bakery and custard review covers that family.
Is diacetyl still in vape juice today?
The 39-of-51 figure is a snapshot of US products from a decade ago, a convenience sample chosen partly for youth appeal. It is not today’s prevalence, and none of the sources read this run gives a newer measurement. The three retailer and explainer pages ranking for this question that this desk read (Vaping360, Vapor Authority, Pod Salt) give no per-compound counts and cite no regulator page.
What does the UK actually say?
The MHRA’s ingredient guidance for Great Britain, updated 16 August 2024, names diacetyl and pentane 2,3 dione in its list of substances that should not be included. It says the list is not exhaustive, and that an ingredient missing from it is not therefore safe. Acetoin did not appear in the list this desk read. Northern Ireland has separate guidance this desk did not read.
Australia’s industrial chemicals regulator, AICIS, said in an evaluation dated 14 January 2022 that both diketones were prohibited ingredients in nicotine vaping products, citing the TGA, and recommended barring them from inhaled products. That is what AICIS reported in 2022; this desk did not verify the current Australian rule.
For what else sits in the bottle, see what is in a vape.
FAQ
Is diacetyl banned in the UK?
MHRA guidance for Great Britain, updated 16 August 2024, lists diacetyl and pentane 2,3 dione among substances that should not be included as ingredients in e-liquids. That is guidance wording, not a named line in the TRPR: Regulation 16, as quoted on the same page, does not name diacetyl. Northern Ireland has separate guidance, not read here.
Which brands contain diacetyl in their vape juices?
The one primary test read here does not say. Allen and colleagues anonymised the products as Brands A to I, covering three large cigarette companies, one independent e-cigarette company and three distributors. No current brand-level list was found in the sources this desk read, so any named-brand claim you see needs its own test behind it.
Does vaping cause popcorn lung?
The sources read here do not establish that. Allen and colleagues cite diacetyl’s association with bronchiolitis obliterans, the disease nicknamed popcorn lung, in exposed workers, and call vaping a potentially widespread exposure that needs evaluating. That is a warning about exposure, not a measured case count among people who vape.
A bottle free of diacetyl is still a bottle of nicotine, an addictive drug, as our nicotine explainer sets out. This site is for adults of legal purchase age in their market only, and nothing here is a reason to start.