Liquids & Aromen

Diacetyl in e-liquids: risks, flavour and safe alternatives

Diacetyl in e-liquids: What the butter flavouring does, why it is controversial and how to recognise diacetyl-free liquids. Guide with tips from Switzerland.

Diacetyl is a flavouring agent found in some e-liquids that imparts a creamy, buttery note – yet it has been the subject of criticism for years. If you’re interested in vaping, you’ve no doubt come across the term: sometimes as a warning, sometimes as a selling point (‘diacetyl-free’). Behind this lies a specific chemical compound with clear properties, but also with risks associated with inhalation that have not yet been fully clarified. Below, you’ll find out exactly what diacetyl is, why it was used in e-liquids, what alternatives are available, and what you should look out for when buying, so that you can make an informed decision.

Diacetyl (chemical name: 2,3-butanedione) is a colourless to slightly yellowish liquid with an intense smell of butter and caramel. The substance occurs naturally during fermentation processes – for example in butter, yoghurt, beer or roasted coffee – and is also produced synthetically in the food industry to give products such as margarine, popcorn or baked goods a buttery flavour profile.

In the e-cigarette world, diacetyl e-liquid was previously frequently used for flavours such as vanilla, custard, popcorn, caramel, pastries or milkshakes. Important: The substance is approved as a food additive in many countries – oral consumption is considered safe. However, when heated and inhaled via a vaporiser, the substance behaves differently, which is why the lungs and respiratory tract are at the centre of the debate. Diacetyl belongs to the group of diketones, which also includes acetylpropionyl (2,3-pentanedione) and acetoin – two commonly used substitutes.

The question ‘Is diacetyl harmful?’ stems from studies conducted in US popcorn factories. Workers who inhaled high concentrations of vapours containing diacetyl over a long period developed a rare lung disease that has since become known as ‘popcorn lung’ (bronchiolitis obliterans). This observation became the starting point for the debate surrounding butter-flavoured vaping.

Difference between occupational exposure and consumer use

The levels of diacetyl measured in e-liquids are significantly lower than those found in industrial settings. To date, there has been no clinically confirmed case of popcorn lung caused by e-cigarettes. Nevertheless, any additional strain on the respiratory tract can be problematic, particularly with long-term, daily vaping.

Regulation in Switzerland and the EU

In the EU, diacetyl has been banned in e-liquids since the 2016 TPD Directive. Switzerland follows comparable standards, and reputable manufacturers have refrained from using it for years. However, products imported from third countries may theoretically still contain the substance – a reason to pay attention to their origin.

To help you find a diacetyl-free e-liquid and avoid any uncertainty, consider the following points:

Check the labelling: Many manufacturers state ‘diacetyl-free’ or ‘DAAP-free’ (diacetyl, acetylpropionyl, acetoin) directly on the label or in the product information sheet.
Check the origin: E-liquids from Switzerland, Germany, France or the UK are subject to strict regulations. Exercise caution with products from non-EU countries that lack clear labelling.
Assess the flavour profile: Custard, popcorn, butter biscuit and ice cream flavours in particular were once typical sources of diacetyl. If in doubt, ask the retailer for a certificate of analysis.
Choose a reputable shop: Specialist retailers based in Switzerland work with certified suppliers and can provide information on the ingredients of every e-liquid.
Be aware of substitutes: Acetoin and acetylpropionyl are used as alternatives, but are chemically related. Some manufacturers avoid these diketones entirely – a plus for sensitive vapers.

Another tip: if you vape a lot (several ml per day), it’s generally worth choosing flavours that are as pure as possible rather than complex dessert blends, as these traditionally rely more heavily on butter and cream notes.

Is diacetyl still permitted in Swiss e-liquids?

In practice, diacetyl is no longer used by reputable manufacturers and shops in Switzerland. Products from the EU are regulated by the TPD anyway. Caution is advised with parallel imports from third countries – check the list of ingredients.

How can I tell if a liquid is diacetyl-free?

The easiest way is to check the product description or the safety data sheet. Indications such as ‘diacetyl-free’, ‘DAAP-free’ or a full list of flavourings provide clarity. If this information is missing, ask the retailer directly.

Does diacetyl really cause popcorn lung when vaping?

To date, there has been no confirmed case of popcorn lung that can be definitively attributed to e-cigarette use. The concern stems from industrial exposure to high doses. Nevertheless, avoiding diacetyl in e-liquids makes medical sense and is now standard practice.

Are custard and dessert e-liquids automatically problematic?

No. Modern custard or pastry e-liquids are produced using alternative flavouring components and are free from diacetyl. Simply check the label or the product information – many manufacturers actively advertise that their products are diacetyl-free.

Diacetyl was a popular flavouring for years, but is now practically never used in Swiss and European e-liquids. Anyone who shops with care, pays attention to ingredient lists and orders from specialist retailers can approach the issue with peace of mind. In our selection of e-liquids, you’ll find tested products with clear ingredient lists – from fresh and fruity 10 ml e-liquids to creamy dessert flavours without any problematic diketones. Take your time to compare the flavour profiles and choose what suits your setup and your taste.