Propylene glycol (PG) is one of the main ingredients in e-liquid, and although most vapers can inhale it without a problem, for a small percentage it can cause an allergic reaction. You can rectify the issue by switching to a vegetable glycerin (VG) based e-liquid.

PG Sensitivity and Allergy Symptoms

For those sensitive to PG, the most common consequence is excessive irritation and a sore, dry throat when inhaling PG-based liquids, but in some cases more typical allergic reactions can occur. These include sinus problems, headaches and nausea, and in some cases numbness of the face and itchy hives.

Between 1.5 and 3.5 percent of people have a contact allergy to PG (although there is some uncertainty about the precise number), and in these cases, small bumps may be present around your mouth, accompanied by a burning or stinging sensation in the affected areas.

Another thing to consider, however, is that there may be some crossover between potential signs of allergies and symptoms from stopping smoking (such as “quit zits”), so the best way to be sure is to stop vaping or use a different e-liquid (see below) for a while to see if the symptoms clear up. If they do, then it’s likely that PG is causing your symptoms.

Finally, it’s worth noting that even vapers who’ve used PG-based liquids before without issues can develop a sensitivity later down the line – just because you’ve been OK before doesn’t mean you won’t develop an allergy or sensitivity.

What to Do if You’re Allergic to PG

The simplest solution for a vaper allergic to PG is to switch to vegetable glycerin (VG) based e-liquids, or ones with much lower amounts of PG. Although most mixers (including Black Note) use both PG and VG in their e-liquid, you can find VG-only liquids, and some mixers allow you to choose your ratio of the two. If you don’t switch to VG-only liquids, try to keep the PG content as low as possible – 70 percent VG to 30 percent PG may be enough to minimize your symptoms, but the less PG the better.

It’s possible to be allergic to VG too, but this is much less common and is unlikely to be an issue.