What is PG?

PG, also known as propylene glycol, is a thin, odourless, natural compound which is faintly sweet and low in toxicity. Derived from propylene, PG is used in many common household products. It is also used in cosmetics, as well as in medicine (like asthma inhalers).

Although propylene glycol is considered to be safe for human consumption, the body metabolizes it as alcohol, so this can be the cause of negative reactions in users with sensitivities.

Uses of PG

PG is used in a wide variety of products, including the following:

• Personal hygiene products (soaps, lotions, deodorant, and lubriants)
• Food and condiments (soft drinks, salad dressings, cake mixes, popcorn, fat-free ice cream)
• Fog machines
• Asthma inhalers
• Household items, such as non-toxic automotive antifreeze

PG in E-liquid

In e-liquid, PG is primarily used for its humectant and solvent properties. However, as vegetable glycerin (VG) is very thick, propylene glycol is also used to thin down e-liquid, making it easier to fill into tanks and absorb into atomizer wicks.

Medical Testing and Studies on PG

Propylene glycol has been approved for inhalable and injectable medicines by all authorities, and is approved for long-term, high-volume inhalation by employee health regulations.

However, there have been many reports of sensitivities or allergies to propylene glycol, resulting in adverse effects. As PG is a humectant and metabolizes in the body as alcohol, it can cause dryness of the mouth and other parts of the body if used in excess. It’s recommended to drink water regularly while vaping to avoid feelings of dryness. PG also contributes to the “throat hit” factor of e-liquid, and can feel harsh when inhaled. Taking temporary breaks from vaping periodically can assist in preventing throat irritation.

Learn more about VG and PG on our vaping wiki.

Related: What is Vegetable Glycerin (VG)?