What ingredients are in e-liquid, and are they harmful to the body?

 　　When discussing the most important component of e-cigarettes, it has to be e-liquid. No matter how powerful the atomizer is, it needs a quality e-liquid to match. First, let’s go through the five main ingredients found in e-liquid.<\/p>   　　Vegetable Glycerin (VG, Propylene Glycol, Natural Glycerin)
  　　What is vegetable glycerin? The vegetable glycerin used in e-cigarettes is generally extracted from plant materials. It is not only used in e-liquids but also in food, cosmetics, and pharmaceuticals. The chocolate cakes we eat contain a lot of vegetable glycerin, which is safe for direct consumption. Toxicological studies indicate that vegetable glycerin is non-toxic and is digested and converted into essential nutrients for our daily needs.
　　In e-liquid, glycerin primarily serves to increase the amount of vapor produced. The higher the proportion of glycerin in the e-liquid, the denser the vapor produced upon heating. If you want to exhale large clouds of vapor, using pure 100% glycerin is an option. However, apart from the natural sweetness of glycerin, there won’t be any other flavors, and the vapor produced will be quite large. But pure glycerin has poor fluidity in cotton, which is commonly referred to as being difficult to wick. If you use a tank atomizer with 100% glycerin, the cotton will struggle to wick properly, leading to burnt hits after a few puffs.
  　　Propylene Glycol (PG)
  　　Propylene glycol can be defined as a colorless, odorless liquid with excellent fluidity. Toxicity studies indicate that it has low toxicity and irritancy, and the amount used in e-liquid typically does not cause issues. However, it is important to note that some individuals may have allergic reactions to propylene glycol, resulting in small bumps on the skin, and it can be somewhat irritating to the throat. Healthy users typically do not experience problems, but those with pre-existing throat conditions may cough or feel discomfort when using high concentrations of PG e-liquid, such as 50% PG / 50% VG. Choosing e-liquids with higher VG content, like 30% PG / 70% VG or 20% PG / 80% VG, can reduce throat irritation significantly.
　　In e-liquid, propylene glycol primarily serves to enhance the mixing of flavorings and provides some vapor production. Due to its structure, vegetable glycerin has difficulty carrying flavorings, making it hard for flavorings to mix evenly in pure VG. Especially in colder temperatures, high VG e-liquids can cause flavorings and nicotine to precipitate and float on the surface. This is normal; warming the e-liquid in your hands and shaking the bottle can help mix the brown nicotine and flavorings back together. Therefore, PG is essential in e-liquid; without it, pure nicotine and flavorings would be difficult to dissolve.
　　Nicotine
  　　Nicotine is easily understood; it is the substance that makes smokers addicted to cigarettes. It is unclear whether nicotine itself is harmful or harmless, as it is also used in treatments for depression. In cigarettes, the real harm comes not from nicotine but from the harmful substances that are inhaled alongside it due to nicotine's allure. Of course, even in e-liquid, one should not arbitrarily mix high doses of nicotine! This is very important—do not risk your health by purchasing nicotine solutions and adding them yourself! Just don’t! If you don’t take risks, you won’t face consequences! Don’t mess around with high nicotine concentrations; normal use should involve gradually reducing nicotine levels. If you find zero nicotine e-liquid too weak, try 3mg; that’s usually sufficient. A 3mg e-liquid is generally safe unless you’re constantly puffing on it, which could lead to mild dizziness—just drink some water to alleviate that!
　　In e-liquid, nicotine serves to enhance throat hit and provide the sensation of smoking, along with a slight stimulating effect. Don’t reject these stimulating sensations as something negative; after all, some vegetables we eat daily, like tomatoes, also contain nicotine.
　　Flavorings
  　　There are countless flavorings, simply put, they are the flavors of e-liquid. Flavorings mainly come from two sources: plant extracts and industrial synthesis. As long as they are from reputable manufacturers, the flavorings used are generally reliable. Don’t assume that foreign e-liquids are superior just because of their materials; as long as the flavorings meet national standards, there shouldn’t be any issues. The beverages we drink daily are also flavored with flavorings, which, apart from lacking nutrition, are not harmful.
　　Additives
  　　Additives differ from flavorings. A quick search online for e-liquid additives will yield many results, including throat soothers, cooling agents, sweeteners, de-sweeteners, and deionized water, among others. These substances are key to perfectly blending flavorings with VG and PG, and normal use poses no significant issues. However, some unscrupulous vendors may use many illegal additives, such as "diacetyl." This substance has been found in many e-liquids, including those from so-called reputable foreign brands. This is why some users find a particular e-liquid flavorful at first but less so over time; it’s due to the removal of these undesirable additives for legal or other reasons. This substance primarily enhances the tobacco flavor and is generally found in nutty or roasted tobacco e-liquids, while fruity e-liquids typically do not contain such additives. There are many other harmful substances, so compared to the previous four ingredients, the uncertainty of additives poses the greatest risk to e-liquid safety.