The unpleasant, burnt taste from a vaping device, often called a “dry hit,” raises questions about the resulting vapor’s contents. Nicotine remains present in the remaining e-liquid and the aerosol produced during this event. However, the extreme heat causes a drastic chemical change in the liquid’s carrier components, not the nicotine itself. This thermal stress compromises nicotine delivery and introduces concerning chemical byproducts into the inhaled vapor.
Why the Vape Tastes Burnt
The harsh, burnt flavor results from the coil overheating the cotton wick instead of vaporizing the e-liquid. A dry hit occurs when insufficient e-liquid reaches the coil to keep the wicking material saturated, often due to low liquid levels, chain vaping, or high-power settings. When the wick runs dry, the coil’s temperature spikes because the liquid is no longer there to absorb the heat.
This lack of liquid causes the cotton material to scorch or burn directly, producing the foul taste. The coil heats the dry cotton and any residual buildup to a much higher temperature than normal. This temperature increase causes chemical decomposition, effectively combusting the wick and residue rather than merely vaporizing the e-liquid.
The Fate of Nicotine During a Dry Hit
Nicotine is a heat-stable molecule, allowing it to survive the regular vaporization process. Although a dry hit generates enough heat to burn the wick and degrade carrier liquids, it is often insufficient to completely neutralize all the nicotine. For instance, nicotine salts are thermally stable, with release temperatures typically between 150°C and 260°C.
The nicotine present in the remaining saturated liquid within the tank is largely unaffected. Even the small amount of vapor produced during the dry hit contains nicotine molecules, mixed with irritating byproducts from the overheated carrier liquids. The primary issue is that nicotine delivery is highly inefficient and accompanied by toxic compounds, not that the nicotine is gone.
Degradation Products and Health Concerns
The most significant concern with a burnt hit is the thermal degradation of the primary carrier liquids: Propylene Glycol (PG) and Vegetable Glycerin (VG). When subjected to the extreme heat of a dry coil, these compounds break down into highly irritating and toxic substances known as carbonyl compounds. This degradation can occur at temperatures as low as 133°C to 175°C, which are easily exceeded during a dry hit.
Overheating VG (Glycerin) produces Acrolein, a volatile aldehyde and severe respiratory irritant. Overheated PG (Propylene Glycol) is a precursor for Formaldehyde, a highly toxic compound and known carcinogen. Repeated exposure to these chemical byproducts can cause inflammation of the airways and potentially damage lung tissue. The extreme heat can also cause the atomizer’s metal components to release trace amounts of metallic particles, such as nickel or chromium, which are then inhaled.