The science behind e-liquids: what’s inside vape juice?

February 18, 2025

Vaping has quickly become a popular alternative to smoking, with millions of people around the world choosing e-cigarettes and vapes as their go-to nicotine delivery system. But have you ever wondered what goes into the e-liquid (or vape juice) that powers your vape device? Let’s dive into the science behind e-liquids and break down the key ingredients that make up your favorite vape juices.

Propylene glycol (PG)

One of the main ingredients in e-liquids is propylene glycol (PG), a colorless, odorless liquid commonly used in food and pharmaceuticals. PG serves as a base liquid in e-liquids and is responsible for the throat hit that mimics the sensation of smoking. It also helps to carry the flavors and nicotine.

Why PG? It has a thinner consistency than vegetable glycerin (VG), which helps to create the desired vapor and flavor.
Potential downsides: some vapers may experience throat irritation or allergies when using e-liquids with higher PG concentrations.

Vegetable glycerin (VG)

The other primary base liquid used in e-liquids is vegetable glycerin (VG). VG is a thicker, sweeter liquid that produces larger vapor clouds, which is why it’s popular among cloud chasers.

Why VG? VG helps to create a smoother vape and is a key ingredient for producing dense clouds. It’s also less harsh on the throat.
Potential downsides: due to its thick consistency, VG can gunk up coils faster than PG.

Nicotine Nicotine

Is the active ingredient in most e-liquids, and it’s what makes vaping so appealing to those who are trying to quit smoking. E-liquids are available in various nicotine strengths, ranging from 0mg to 20mg and higher.

Nicotine salts vs. freebase nicotine: Nicotine salts are a newer innovation and are smoother at higher nicotine concentrations, making them more suitable for people who are transitioning from cigarettes. Freebase nicotine, on the other hand, has a higher pH, which makes it more harsh and is typically used for lower nicotine levels.
Why Nicotine? Nicotine is addictive, but for smokers transitioning to vaping, it offers a safer alternative compared to smoking tobacco.

Flavorings

Flavor is one of the key reasons why vaping has become so popular. From fruity and sweet to menthol and dessert-inspired flavors, the wide variety of e-liquid flavors is a major selling point for vapers.

How are flavors made? Flavorings used in e-liquids are typically food-grade ingredients that are safe for consumption. However, not all flavorings are safe to inhale, which is why it’s important to purchase from reputable brands.
Why flavoring matters: The right flavor can enhance your vaping experience and make it more enjoyable.

Additives and enhancers

Some e-liquids also contain additives or enhancers to improve the taste or performance of the liquid. These can include sweeteners, menthol, or other compounds that affect the viscosity, flavor, or throat hit.