Is There Diacetyl In E-liquid?

Updated 1st May 2025

Over recent weeks we have seen ever more news articles linking vaping with suspected cases of Popcorn Lung. Many of these articles incorrectly report that some e-liquids use diacetyl as an ingredient. Other news stories also fail to mention that these alleged cases of popcorn lung occur in countries where diactyll isn’t prohbited, like the USA.

Diacetyl has been banned as an ingredient for vapes and e-liquid in the UK since 2016. UK regulations prohibit diacetyl in any vape products sold in the UK.

Tobacco cigarette smoke on the other hand, contains 301-433 ppm of diacetyl.

Let's look in more detail at diacetyl and how it got its reputation in the vaping market.

What is Diacetyl?

How is potential exposure related to harm, and the lung disease commonly known as popcorn lung?

Vapers have picked up bits and pieces of information from social media or via a Google search. But they still remain confused as to whether this should be a major concern for a vaper? It's an understandable conundrum as there is a lot of conflicting information online. However it really is of no concern whatsoever. Let's have a look at some facts about diacetyl and its potential to cause harm to a vaper.

The Science Bit - Diacetyl

First, let's discuss the chemistry. Diacetyl (aka 2,3-butanedione) is an important flavour compound. It occurs naturally in some dairy products, wines, and beers. Occasionally manufacturers add it to products to enhance flavour. In wine, diacetyl has a buttery aroma and adds complexity to the sensory impact of the wine. It is a prominent volatile (easy to evaporate) constituent of buttery flavourings and the flavouring industry uses it extensively. Diacetyl is widely accepted as a safe flavouring additive and can be found in the food we consume daily.

Diacetyl and Popcorn Lung

Working with buttery flavourings and heated soybean oil was associated with high exposure to diacetyl vapour. Much higher than in than other areas of the plant. People who had worked as mixers for more than 12 months were more likely to develop respiratory symptoms. The term 'popcorn worker’s lung' described this airway damage that some workers suffered. Subsequent toxicology studies have shown that vapour from heated butter flavourings can cause damage to the airways in animals. Overall, the body of evidence points to diacetyl as one agent that can potentially cause lung damage.

Popcorn lung symptoms and testing

So you might ask yourself what all the fuss is about!? Well, years of studies conducted by scientists have established the safety of diacetyl as a food additive. However, the average person would only breath in trace amounts of vapourised diacetyl through the food that they eat. Back in 2002, Occupational health scientists in the USA conducted studies at six microwave popcorn plants. They wanted to determine if diacetyl exposure had contributed to some rare cases of lung disease among the factory workers. Symptomatic workers had developed an irreversible type of lung damage called bronchiolitis obliterans.

Diacetyl and vaping

This sounds terrible, I can hear you saying! Let's bring the discussion back to the context of vaping. As you all know, there are a vast array of flavoured e-liquids on the market for you to pick from. Way back in 2014-16, sweet dessert-type flavours had grown increasingly popular. A minority of e-liquid manufacturers were using butter-type flavourings that we would deem unsuitable for inhalation. The press and several scientific journals have documented this.

But we must consider a principle of toxicology that the level of exposure matters. 'The dose makes the poison', to paraphrase toxicology pioneer Paracelcus. The popcorn plant workers and laboratory animals experienced far higher levels of vapourised diacetyl than any vape aerosol could contain. And that’s only if the e-liquid in question contained it as a minor ingredient component. Indeed, tobacco cigarette smoke contains 301-433 ppm of diacetyl per cigarette. But no smoker has ever been diagnosed as contracting “popcorn worker’s lung”. This level is far higher than any previously reported in vape aerosols. So we must bear this in mind when we evaluate the risk posed by diacetyl from vaping. It was always small, but nowadays it really is pretty much zero.

All products sold in the UK must be notified and regulated with the MHRA. This means that no products legally available for sale in the UK will contain diacetyl.

Does e-liquid contain Diacetyl?

In 2016 the Medicines and Healthcare products Regulatory Agency (MHRA) issued some draft guidance. Within this it listed ingredients that vape manufacturers must not include in their e-liquid. Of course, the list included diacetyl (DA) and acetyl propionyl (AP). All products sold in the UK must be notified and regulated with the MHRA. Because of this, no products legally available for sale in the UK will contain diacetyl.

Does vaping cause Popcorn Lung?

There has never been a single confirmed case of “popcorn lung” reported in people who use e-cigarettes. So yes, speculatively it could once have been an issue. But it never was, and certainly cannot happen now.

How do we at Totally Wicked make sure we do it right?

The best way to ensure the safety of the e-liquid you are vaping is to buy from a reputable UK manufacturer. At Totally Wicked we manufacture all our Diavlo, Red Label, Switz and VLTZ e-liquid at our own HQ. That’s right here in Blackburn, UK.

With an ever-expanding e-liquid industry and an ever-expanding body of knowledge regarding e-liquids, it is really important to understand exactly what you are buying.

Qualified toxicologists carefully check all our e-liquid ingredients for inhalation suitability . We notify the ingredients of each and every one of our e-liquid products to the MHRA. Our team provide an emissions test results for every flavouring element. We also make sure MHRA has sight of all of the ingredient toxicology reports we commission. After that we make sure that every mix, and every bottle from that mix, meets our high quality standards.

We know how important it is to do this right. Know what you are vaping!