PG (Propylene Glycol) vs. VG (Vegetable Glycerin)
When it comes to e-juice, two terms constantly crop up: PG and VG. This can seem confusing to the newcomer, but knowledge of these two ingredients can vastly improve your vaping experience. Here’s our easy-to-follow guide on everything you need to know about PG and VG.
What are PG and VG?
In simple terms:
- PG and VG are the odorless liquids that are combined with flavor and nicotine to create e-juice
- Both PG and VG belong to the alcohol chemical class (despite the name, they are not intoxicating). Though e-liquid is sometimes called “oil,” it isn’t really oil at all. It is water solvable and can’t cause any of the medical issues — like lipoid pneumonia — that inhaling actual oils can.
- They produce vapor when heated to relatively low temperature, which allow them to be inhaled.
- The two fluids have a different consistency to each other, and also have a slightly different taste.
- They have distinct mouth and throat sensations when vaped.
- Most modern e-liquid uses a combination of the two fluids, though the ratio can vary dramatically.
- Some vaping set-ups can only work with a certain level of PG and VG.
Choosing the wrong PG/VG ratio can put first-timers off so be careful to choose the right level for your equipment.
Now let’s take a look at each in more detail.
PROPYLENE GLYCOL (PG)
What exactly is it?
Propylene Glycol Chemical Structure
PG stands for Propylene Glycol, a petroleum by-product. The fluid has no odor or color, and is less viscous than VG. In vaping it is used to provide a ‘throat hit’, which some users claim is similar to the sensation experienced when smoking tobacco. It also carries flavor more effectively than VG, meaning it’s the most commonly used suspension fluid for flavor concentrates.
How is it used?
Propylene Glycol can be found in various common household items. Amongst others, these include:
- Nicotine inhalers
- Toothpaste and other oral hygiene products
- Medical products used orally, injected or as topical formulations
- Pet food
- Beauty products, including make-up, shampoo and baby wipes
Is it safe?
Studies have shown that PG is safe to ingest orally, and the FDA has deemed it “generally recognized as safe” to be used as a food additive. Of the limited studies that exist, a long-term experiment held in 1947 judged that inhaling PG was ‘completely harmless’.
What should I be aware of when vaping PG?
Some people find a high level of PG irritating to the throat. True allergies to PG are rare, but have been reported. If you find yourself coming out in a rash, or suffering other unpleasant reactions after using PG-based e-fluid, you may have a more common mild sensitivity to PG, and should look at using high-VG juice instead.
The most common side effects of using e-liquid containing propylene glycol are dry mouth, sore throat, and increased thirst. These symptoms usually last anywhere from a few days to a week as the body gets used to the propylene glycol. It is advised to drink more water and liquids then usual for the first few weeks of using your e-cigarette. Be aware that any unusual reactions could be side effects from quitting smoking, and not necessarily because of the PG.
VEGETABLE GLYCERIN (VG)
What exactly is it?
VG stands for Vegetable Glycerin. It is a natural chemical, derived from vegetable oil, so is safe for vegetarians. It is commonly used in e-liquid to give a ‘thick’ sensation to vapor. VG has a slightly sweet taste and is considerably thicker than PG. The hit from a high VG fluid is a lot smoother than with PG, making it more suitable for sub-ohm vaping.
What is it used for?
Again, it can be found in numerous medical, food and personal care products:
- Sweetener as sugar replacement
- Beauty products, such as make-up, mousse, bubble bath, aftershave, and deodorant
- Pet food
- Soap and hand cream
- Food such as baked goods, to increase moisture
- To provide thick gel for certain medicinal creams, capsule pills and jellies
- Toothpaste and other dental care products
Is it safe?
The FDA has classified VG as “generally recognized as safe” and it is widely regarded as one of the most benign substances known to man. The SIDS assessment profile show it to have low toxicity when consumed, and of low potential to irritate the skin or eye. This, along with the widespread use of VG in food and medicine suggest it is safe for humans. However, as with PG, there are limited studies on VG being inhaled as opposed to ingestion.
A 2008 study of the toxicity of inhaling aerosolised glycerol found minimal risks. We can assume the use of VG in vaping has no serious impact on health but, as with PG, we would welcome more detailed studies.
It is important to note that the risk of being allergic to vegetable glycerin is very low, making it a useful alternative for people who have issues when vaping e-juice containing PG. If you are allergic to palm oil or coconut oil then VG could prove a problem, but this is relatively uncommon. Diabetics could possibly experience problems with metabolizing VG, but this would not be an issue at the levels used in vaping.
What should I be aware of when using VG?
Most of the modern rebuildable atomizers can handle the thickness of VG but you should be aware that because of that thickness it can pose a problem for some atomizers, specially those with a replaceable pre-built coils (largely due to the high density of cotton in them). High VG liquids will not work well, if at all, in certain tanks. Older products are especially susceptible, particularly models that use smaller coils such as clearomizers. The Nautilus range, Innokin iclears and eGo tanks are some of the more well-known tanks that are known to have difficulties dealing with high VG fluid.
The most common side effect of vaping high VG e-liquid is a dry mouth, sore throat (rare), and increased thirst. Again, be sure to drink plenty of water and take a break from vaping if necessary.
What PG/VG ratio should I use?
There isn’t a one-size-fits-all answer to this. It depends on the kind of vaping experience you prefer. Many people use various levels of PG and VG for different purposes:
- Throat Hit – If you enjoy a sharp throat hit when vaping then you’ll prefer a high PG vape. The ‘kick’ at the back of the throat, is something many ex-smokers crave, and PG (along with the nicotine) provides more of this than VG. PG carries flavour marginally better than VG, so the flavour will be slightly improved.
- Smoothness – High VG fluid tends to give a much smoother feeling on the throat, with a more substantial ‘thicker’ mouthfeel. The flavour is slightly muted in VG fluids, but this can be countered by using more power to produce more vapour. Be careful to stay within the voltage/wattage limits of your atomiser, or you risk dry hits, or even damaging your equipment.
- Stealth Vaping – If you want to keep your vaping lowkey in public then high PG is the way to go. Less vapour is produced when exhaled, making this ideal for the less ostentatious vaping enthusiast. However, you should always apply common sense. Vaping in certain places, such as waiting rooms and on public transport, is often outlawed and is simply bad manners. As vaping is relatively new, we have a duty to be aware of public opinion and behave responsibly.
- Cloudchasing – Cloudchasing involves exhaling dense clouds of vapor, the thicker the better. There are even competitive events based around this activity, where the person producing the biggest clouds wins. If this appeals then high VG is the only option – the higher the better.
The basics of PG and VG are quite easy to grasp. They both work in different ways, and each has advantages and disadvantages. Our advice is to start with a 50-50 PG to VG ratio then try out various combinations and see which you prefer. Make sure your vaping set-up can deal with the different ratios.
Many vapers like to use different levels of PG and VG at different times, and with various devices and flavors. Fruits and beverage flavors often go well with PG, as the sharpness of the PG blends well with the tart or fizz of the flavoring. Similarly, flavors based on cream, custard and yogurt tend to work well with high VG as the thick mouth sensation adds to the dessert-like feel. But as ever, there are no fixed rules, just follow what your taste buds tell you!