Vaping without nicotine has become a popular choice for individuals who enjoy the physical sensation and flavors of e-cigarettes but wish to avoid the addictive chemical. Removing nicotine does not make the aerosol harmless, as the liquid still contains several other components that are heated and inhaled. Understanding the makeup of this e-liquid is necessary to assess the potential impact of nicotine-free vaping. The non-nicotine liquid is fundamentally a chemical solution comprised of a base, flavoring compounds, and various minor additives.
The Primary Carriers: Propylene Glycol and Vegetable Glycerin
The majority of any nicotine-free vape liquid is composed of two primary carrier liquids: propylene glycol (PG) and vegetable glycerin (VG). These compounds are responsible for producing the visible aerosol cloud when heated by the device’s coil. Both PG and VG are classified as food-grade substances, meaning they are considered safe for ingestion, but their safety profile changes when they are vaporized and inhaled.
Propylene glycol is a synthetic organic compound that is colorless, nearly odorless, and possesses a faint, sweet taste. It serves as an effective solvent, meaning it binds well with flavorings, ensuring the vaper experiences the intended taste clearly. PG is also responsible for delivering a sensation often described as a “throat hit,” which mimics the feeling of inhaling traditional cigarette smoke. Because it is thinner in consistency, a higher PG ratio can be used in smaller, lower-power vaping devices.
Vegetable glycerin is a naturally sourced liquid, typically derived from plant oils like palm, soy, or coconut. This thick, viscous liquid is mildly sweet and produces a substantially larger, denser vapor cloud than PG. A higher VG ratio is preferred by vapers seeking maximum cloud production and a smoother sensation on the throat. The ratio of PG to VG is a primary factor in the overall vaping experience, balancing flavor intensity, throat sensation, and vapor volume.
Chemical Flavorings and Minor Additives
Beyond the carrier liquids, the next largest component of nicotine-free e-liquids is the blend of chemical flavorings. These flavorings are complex chemical compounds designed for ingestion and are not necessarily tested for safety when inhaled. Many flavorants are concentrated at levels that can range from 1% to over 20% of the total liquid volume.
A primary concern involves diketones, which are chemicals added to impart rich, creamy, or buttery notes to the flavor profile. Diacetyl, for example, is a diketone traditionally used in foods for its distinct buttery flavor. When inhaled, diacetyl has been strongly linked to bronchiolitis obliterans, a severe and irreversible lung disease often called “popcorn lung.”
Other related diketones, such as acetyl propionyl (also known as 2,3-pentanedione) and acetoin, are used as substitutes but present similar respiratory concerns upon inhalation. Acetoin is problematic because it can degrade over time into diacetyl within the e-liquid solution. Other minor additives include sweeteners like sucralose and ethyl maltol to enhance the sweetness, as well as trace amounts of distilled water or alcohol to adjust the liquid’s viscosity.
Health Concerns Associated with Non-Nicotine Ingredients
The health implications of nicotine-free vaping stem directly from the act of heating and inhaling the base liquids and flavorings. When the carrier liquids, PG and VG, are heated to high temperatures, they can undergo thermal decomposition. This process creates toxic carbonyl compounds that are then inhaled.
Formaldehyde, a known human carcinogen, and acrolein, a severe respiratory irritant, are two such compounds formed when PG and VG break down at high heat. This thermal degradation can occur with what vapers call a “dry hit,” but studies have shown toxic chemical emissions occur even at lower temperatures. Both PG and VG aerosols themselves have been shown to cause irritation and inflammation in the airways.
Inhaling the heated flavor compounds introduces another layer of risk, even separate from the diketones. Flavorants like benzaldehyde (used for cherry and almond flavors) have demonstrated cytotoxicity, meaning they can be toxic to cells in the respiratory system. Similarly, cinnamaldehyde (which provides a cinnamon flavor) is known to be harmful to endothelial cells. The core distinction is that a substance being safe to eat does not mean it is safe to be atomized into an aerosol and drawn deep into the lungs.