As vaping technology has progressed, e liquids have shifted from predominantly high-nicotine blends with propylene glycol (PG) as the dominant diluting liquid to juices that contain less nicotine and are more reliant on vegetable glycerin (VG) to dilute the mixture of flavor extracts and liquid nicotine.

PG and VG have always been used in combination to make e liquids, but with a shift in the market a change in vaper preferences has occurred. PG is the thinner of the two dilatants, and can impart a slightly sweet yet harsh taste when vaporized – it's thought to add to the 'throat hit' that's primarily delivered by nicotine and is sought after by former tobacco users in replicating the feel of smoking. The thin, watery nature of PG was necessary in older-style cartomizers and clearomizers, as the heavier, syrupy VG couldn't pass through wicking material quickly enough to avoid burning and dreaded 'dry hits' of charred silica or cotton wicking.

In the last two years, larger coils packed with cotton or cotton synthetics including rayon have become more common. These coils and wicks are much better suited to absorbing and vaporizing large quantities of liquid, leading to greater cloud production and increased liquid consumption. As vapers consume more e liquids, they're finding that the concentration of nicotine per milliliter can be greatly reduced.

But how do high-VG liquids affect the body? What are the symptoms of VG sensitivity, and how can they be addressed?

First off, it's much more likely you'll experience a negative reaction with PG-heavy liquids, with as many as one in ten new vapers reporting issues. From an earlier post on PG sensitivity:

Most often, complaints revolve around sore throats and upper respiratory tract irritation from former smokers, as some of the chemical additives found in cigarettes but not in e liquids are designed to mask the harshness of a nicotine inhale. More rare (about 1 in 5,000) are reports of dry skin, itchiness, or acne breakouts, and in even more extreme cases (1 in 100,000) users already suffering from tinnitus (a consistent ringing in the ears) will report a worsening condition after starting to vape.

Most users reporting the common sore throat after switching to vaping find that their irritation goes away with time, but for vapers with one of the more persistent conditions, a switch to liquids that rely heavily on vegetable glycerin as a base ingredient is recommended. Making the switch to 100% VG-based liquids is difficult, however, as the vast majority of flavor extract manufacturers suspend their flavoring in PG. Whenever possible, we include notes on the PG/VG content of our liquids to help users select a blend best suited to their needs.

This isn't to say that some vapers don’t experience problems with high-VG liquids (though reported instances of problems are estimated at close to 1 in 5000). Again going back to our earlier post, here are some things to look for:

It's still unknown whether these users are sensitive to vegetable glycerin in general, or rather one of the common plants (usually palm or soy) used in extraction. Common complaints include a 'heavy' feeling in the lungs when breathing after an extended vaping session. For vapers feeling a heaviness in the chest, we recommend trying liquids with a 50/50 PG/VG blend or higher.

This 'chest heaviness' can express itself in a handful of ways, though the most common are labored breathing during a period of intense vaporizer use (the user would probably have experienced similar or worse symptoms while smoking heavily or in a smoke-filled environment) and excess mucus buildup in the mouth or throat.

If you're experiencing any of these symptoms, it's a good idea to consult with your doctor and tell him or her that you've been experimenting with vaping in order to reduce or eliminate your dependence on cigarettes. While we at Breazy are firmly convinced vaping is a healthier alternative to smoking (though it's likely not a risk-free practice), medical professionals, many of whom are beginning to realize the potential of vaping to combat the known evils off tobacco use, should be your ultimate guide when it comes to combating adverse side effects to consuming any substance.