VG (vegetable glycerin) and PG (propylene glycol) are the two base liquids in virtually every e-liquid. They create the vapor you inhale, carry the nicotine and flavorings, and together make up 90% or more of what’s in the bottle. The ratio between them shapes everything about your vaping experience: how thick the clouds are, how strong the throat hit feels, how intense the flavor tastes, and which devices you can use.
What PG and VG Actually Are
Propylene glycol is a thin, odorless synthetic liquid. Its chemical name is propane-1,2-diol. It dissolves other compounds easily, which makes it an effective carrier for flavoring concentrates and nicotine. Outside of vaping, PG shows up in food products, cosmetics, and pharmaceutical preparations. The FDA classifies it as Generally Recognized as Safe (GRAS) for use in food, with permitted levels ranging from 2% in most foods up to 97% in seasonings and flavorings.
Vegetable glycerin (propane-1,2,3-triol) is a thicker, slightly sweet liquid typically derived from plant oils like soy, palm, or coconut. That extra hydroxyl group in its molecular structure is what makes it noticeably more viscous than PG. VG is also widely used in the food and cosmetics industries. Its thickness is so pronounced that it generally can’t be used on its own in e-cigarettes because it wouldn’t wick properly into the coil.
How They Change Your Vaping Experience
PG and VG each bring something different to the table, and the balance between them determines what vaping actually feels like.
Throat hit: PG delivers a sharper, more pronounced sensation at the back of the throat, closer to what cigarette smokers are used to. Because PG lacks VG’s natural sweetness, many vapers describe the hit as more assertive and direct. Higher PG ratios amplify this effect, which is why people transitioning from cigarettes often prefer PG-heavy liquids.
Vapor production: VG is responsible for thick, visible clouds. Research from a study published in Psychopharmacology confirmed this directly: e-liquids with 73% VG produced significantly larger and more visible aerosol clouds than liquids with no VG at all. Increasing VG concentration alongside higher device wattage is the standard approach for cloud chasing.
Flavor intensity: PG is the better flavor carrier of the two. It dissolves flavoring compounds more completely and doesn’t add its own taste to the mix. VG, on the other hand, has a mild sweetness that can slightly mute flavor profiles. E-liquids with very high VG content often taste a bit less sharp and defined than their higher-PG counterparts.
Common VG/PG Ratios and What They’re For
Most commercial e-liquids use one of a few standard ratios, expressed as VG/PG:
- 50/50: The most versatile option. It balances flavor clarity, a moderate throat hit, and reasonable vapor production. Works in nearly any device, making it a safe default choice if you’re unsure what to pick.
- 70/30 VG/PG: The sweet spot for vapers who want noticeably thicker clouds without completely sacrificing throat hit or flavor. This is one of the most popular ratios for sub-ohm vaping.
- 80/20 VG/PG: Favored by cloud chasers. Produces dense vapor but delivers a softer throat hit and slightly muted flavor. Requires higher-powered devices to vaporize properly.
- 60/40 PG/VG (or higher PG): Prioritizes throat hit and flavor sharpness over cloud size. The thinner consistency works well in smaller, lower-powered devices.
Matching Your Ratio to Your Device
Getting the VG/PG ratio wrong for your hardware is one of the most common causes of dry hits and leaking. The key factor is viscosity: high-VG liquids are thick, and not every device can handle them.
Pod systems and mouth-to-lung (MTL) tanks have small wicking ports designed for thinner liquids. They work best with 50/50 blends or PG-heavy ratios. Pushing a 70/30 VG/PG liquid through a basic pod system often means the wick can’t absorb juice fast enough, leading to dry, burnt-tasting hits.
Sub-ohm tanks and direct-lung setups have larger juice channels and higher-powered coils. These handle 70/30 or 80/20 VG/PG liquids without issue because the bigger wicking holes let thick juice flow freely, and the extra heat vaporizes it efficiently. Running a thin, high-PG liquid in a sub-ohm tank can cause the opposite problem: the juice flows too freely and leaks out of the airflow holes.
Side Effects and Sensitivities
Both PG and VG are associated with some short-term side effects when inhaled. Commonly reported symptoms include nausea, dizziness, lightheadedness, headache, and skin or lung irritation. In one small study tracking vaping sessions, most participants experienced at least one symptom during a 20-minute session, with lightheadedness being the most frequent. The number of symptoms correlated with how much aerosol was retained in the lungs.
PG in particular can cause a sore or burning throat and noticeable mouth dryness when used at high ratios. This happens because PG is hygroscopic, meaning it absorbs moisture from the surrounding tissue. Some vapers also develop a tickly cough or mild dehydration-related discomfort. If you consistently experience throat irritation or dryness, switching to a higher VG ratio often helps, since VG is gentler on the throat even though its sweetness can gum up coils faster.
True PG sensitivity isn’t well quantified in terms of prevalence, but it’s a recognized issue in the vaping community. Symptoms typically include persistent throat irritation, coughing, and occasionally mild skin reactions. People who suspect a sensitivity usually start by moving to a 70/30 or 80/20 VG/PG blend to see if symptoms improve.
GRAS Status vs. Inhalation Safety
One point of confusion worth clearing up: both PG and VG hold FDA GRAS status, but that designation applies specifically to ingestion in food. It says nothing about the safety of heating these liquids and breathing them into your lungs. The respiratory system processes substances very differently than the digestive system.
Lab research has shown that PG and VG exposure can interfere with how airway cells take up and metabolize glucose, a basic energy process. This is an in vitro finding (cells in a dish, not people), but it highlights that “safe to eat” and “safe to inhale repeatedly” are separate questions. The long-term effects of daily inhalation over years remain an active area of study, and the current evidence base doesn’t yet offer definitive answers on cumulative risk.