Propylene glycol (PG) in e-liquid: function and selection

Propylene glycol (chemically 1,2-propanediol), often spelled propylene glycol and abbreviated as PG, is a clear, virtually odourless liquid with a slightly sweet taste. The substance is used in the food and cosmetics industries as a humectant and carrier, where it bears the E number E 1520. In e-liquids, PG, together with vegetable glycerine (VG), forms the so-called liquid base – the framework that carries flavours and, where applicable, nicotine.

Unlike VG, propylene glycol is thin and has a significantly lower viscosity. As a result, it is quickly absorbed into the cotton of a coil and binds flavours efficiently. Do not confuse PG with ethylene glycol – this is a toxic antifreeze and has no place in e-liquids. Reputable manufacturers use only pharmaceutically pure PG (USP/EP grade).

Propylene glycol performs several functions simultaneously in every e-liquid. It acts as a flavour carrier, a humectant and is responsible for the so-called throat hit – that slight tickle in the throat that many people switching from tobacco cigarettes expect.

Flavour and throat hit

The higher the PG content, the more intense the flavours become and the more noticeable the throat hit is. Fruity and menthol e-liquids benefit particularly from a higher PG content, as the flavour molecules dissolve better in PG than in VG.

Vapour volume and coil behaviour

VG produces the visible clouds, PG delivers the flavour. A 50/50 PG/VG ratio is the all-rounder for pod systems and MTL (mouth-to-lung) vapes. Sub-ohm setups with high wattages (60 W and above) often use a 30/70 or 20/80 ratio in favour of VG, as otherwise thin e-liquids would flood the cotton.

Before choosing an e-liquid or base, it’s worth considering the following points:

• PG/VG ratio suitable for the device: Pod systems and disposable vapes tolerate 50/50 to 60/40 PG/VG. Sub-ohm tanks require more VG (usually 70% or higher), otherwise the e-liquid will drip through the coil.
• Quality and purity: Look for pharmaceutical-grade PG in USP or EP quality. Reputable manufacturers state this on the label.
• PG intolerance: A small proportion of vapers experience a scratchy throat, dry mouth or skin reactions. If you notice this, switch to high-VG e-liquids (80/20 VG/PG) or VG-based formulations.
• Adjusting nicotine strength: PG-rich e-liquids intensify the throat hit. If you combine a 50/50 mix with 18 mg/ml free-base nicotine, it will feel harsh. Nicotine salt or lower strengths are more pleasant in this case.
• Storage: Propylene glycol is hygroscopic and attracts moisture. Store e-liquids in a cool, dark place and keep them tightly sealed to preserve flavour and consistency.

If you’re mixing your own blends, use pure PG and VG bases as well as flavour concentrates and dose to your liking. Ready-made shortfills and longfills save you this work and provide a balanced ratio straight from the bottle.

Is propylene glycol harmful to health?

PG is considered safe for consumption and in cosmetics, and is approved as a food additive in the EU and Switzerland. Long-term data on inhalation in e-liquids is limited; acute toxicity has not been demonstrated at typical levels.

What does PG/VG 50/50 mean?

The ratio indicates the percentage composition of the base. 50/50 means half propylene glycol and half vegetable glycerine – a balanced ratio with good flavour, moderate vapour and a clear throat hit.

Why does my e-liquid cause a scratchy sensation in my throat?

A pronounced throat hit may be due to a high PG content, excessive nicotine strength, or individual intolerance. Try a liquid with 70% VG or reduce the nicotine strength and see if that makes a difference.

Can I vape pure PG?

Theoretically yes, but not practical. Without flavourings, pure propylene glycol tastes slightly sweet to neutral, but the throat hit is very intense. For everyday use, mixed bases with flavourings are the better choice.

Propylene glycol is therefore far more than a simple filler: it determines the flavour, vapour production and throat hit of your e-liquid. Those who find the right PG/VG ratio for their device will get significantly more enjoyment from their e-cigarette. Take your time browsing through our e-liquids and nicotine-free bases, compare the mixing ratios and try out different variants until you’ve found your personal favourite. This range is intended for adults aged 18 and over.