At first glance, a post that looked like a food recipe was recently uploaded to an online e-cigarette community. It was a so-called "liquid kimjang" method for making the liquid used in e-cigarettes yourself. The post listed the mixing ratio of the solution and flavorings, production steps, and maturation period. Dozens of comments asked for specific manufacturing methods.
As of the 22nd, about 850 "liquid kimjang" methods could be found on this community. Questions and answers from users attempting to make liquid themselves for the first time numbered in the tens of thousands. Websites and purchasing routes for various flavorings and ingredients were actively shared. A dedicated calculator that computes the ratios needed for liquid making has even appeared.
Why are more people trying to make e-cigarette liquid themselves? Are there no safety issues? Out of sudden curiosity, we spoke with cigarette retailers and experts.
◇ Mixing ingredients and maturing in "liquid kimjang"… interest grows ahead of price hikes
Liquid kimjang refers to directly blending e-cigarette liquid and letting it mature for a set period. Users nicknamed it "kimjang" because the process is similar to making kimchi. It is usually made by mixing propylene glycol (PG), vegetable glycerin (VG), and flavorings. Related information and tips are easy to find on YouTube and social media (SNS).
Liquid kimjang has mainly been shared among e-cigarette users seeking to create scents and concentrations suited to their tastes. Recently, however, interest has grown as people aim to avoid the burden of higher prices.
A revised Tobacco Business Act that took effect on Mar. 24 served as the trigger. The amendment defines as tobacco not only leaf tobacco but also products that use nicotine as a raw material. As a result, e-cigarette liquid is now included in the definition of tobacco and is subject to a surtax of 1,823 won per ml. By simple calculation, the price of a 30 ml bottle that sold in the 20,000 won range could rise by up to three times.
Tobacco shops are still selling liquid inventory manufactured or imported before the law took effect and thus not subject to the surtax. But store owners say price hikes are inevitable once inventory runs out. A manager at an e-cigarette shop in Songpa District, Seoul, said, "One customer bought 200 bottles of liquid at once before prices go up," adding, "Once inventory runs out, it will be hard to sell at current prices."
◇ As online sales are blocked, concern grows over "DIY manufacturing" as a workaround
While tighter regulations are expected to reduce youths' access to liquid-type e-cigarettes, concerns are also emerging online that DIY manufacturing could become another workaround.
Liquid-type e-cigarettes have long been criticized for falling into a regulatory blind spot because many products did not legally qualify as tobacco. In particular, problems of youths accessing liquid-type e-cigarettes through 24-hour unmanned e-cigarette shops or online sales routes have been raised repeatedly. According to the Korea Disease Control and Prevention Agency, the rate of liquid-type e-cigarette use among high school students rose from the 2% range in 2020 to the 4% range in 2024.
After the revised Tobacco Business Act took effect, sales of e-cigarettes via shopping malls or SNS are restricted. Convenience stores and unmanned vending machines also must conduct adult verification procedures. Authorities believe these measures will reduce youths' access to e-cigarettes.
The problem is that the stricter the regulations, the more some users may turn to DIY methods instead of finished goods.
On online communities, questions like "I'm trying to make it for the first time," "Where do you buy ingredients?" and "How do you set the ratios?" keep appearing. Observers say it is hard to rule out the possibility that liquid kimjang will spread as prices for finished goods rise and purchasing routes shrink.
◇ "Analog nicotine" can also be bought online… mixing ingredients outside regulation and inhaling
Another factor fueling the spread of liquid kimjang is the relative ease of obtaining analog nicotine products. Analog nicotine refers to chemicals with a molecular structure similar to nicotine that may produce nicotine-like effects but, in some cases, do not legally qualify as nicotine. Six-methylnicotine, marketed for human inhalation, is a representative example.
Online, it is easy to find businesses selling analog nicotine, nicotine-free liquid, and flavorings. One e-cigarette vendor posted a notice saying, "All products shipped from Apr. 24, 2026 will be produced with six-methylnicotine."
These products are sold on the grounds that they can evade existing nicotine regulations, but concerns about safety are high. In particular, when individuals directly mix multiple chemicals, heat them with an e-cigarette device, and inhale, it is difficult to know what reactions may occur. There is also the possibility that impurities are introduced during manufacturing or that concentrations are set incorrectly.
◇ Expert: "Inhaling gases is a different matter… the seriousness must be recognized"
Experts warn that liquid kimjang can cause serious health problems. Some ingredients used in liquid manufacturing may be substances used in food or cosmetics, but heating and inhaling them into the lungs is an entirely different matter.
Finished goods distributed on the market are subject to ingredient labeling and related regulations during manufacturing and import, but it is difficult to verify the mixing concentration or contamination of liquid made by individuals. The manufacturing methods circulating online are not safety-verified. Even with the same ingredients, the substances inhaled can vary depending on ratios, maturation time, heating temperature, and device type.
Lee Seong-gyu, head of the Korea Tobacco Control Research and Education Center, said, "Ingredients used to make liquid may be safe upon contact or ingestion, but after heating and inhalation, most cause serious side effects," adding, "People need to recognize that liquid kimjang can cause serious health problems."