Find out if you are allergic or sensitive to PG, and what to do if you are….
Somewhere between the failed cold turkey attempt and the disappointing experience with Chantix, he’d lost hope. He started to feel like he was just destined to die prematurely with battered, barely-functioning lungs.
But seeing a friend vaping had changed all that.
‘Maybe quitting is possible after all,’ he thought, ‘maybe I can do it.’
As he felt the hope for a healthier, longer, happier life start to swell up inside him, it happened. When he puffed on his new pen-sized device and took the vapour down into his lungs, an unbearable scratching, burning sensation overcame his throat.
He hacked up a cough, spluttering a messy cloud of strawberry-scented vapour out in front of him.
He tried again and again.
‘It must be my technique,’ he thought. ‘Maybe I’m just getting used to inhaling droplets of liquid instead of tar-filled smoke.’ But every time he tried, the result was the same. Vaping was more painful than smoking.
As the minutes passed and his nicotine craving went unfulfilled, he found himself reaching for the half-empty pack of cigarettes he’d promised himself he’d be throwing away by the end of the week…
If the above sounds like your experience with vaping, you’re not alone. There are many reasons you might have a bad reaction to vaping, but one of the most likely culprits is propylene glycol (PG). If you spend a little bit of time browsing vaping forums and talking to smokers and vapers, you’ll quickly learn that not everybody can tolerate it.
A common explanation is that some people are just allergic to PG. But it’s not that simple.
In fact, while allergies do happen, in situations like the one dramatised above, it’s normally something a lot more common but arguably just as unpleasant: PG sensitivity.
PG Basics: What is it and Where is it Found?
Propylene glycol is a colourless, odourless and near-tasteless molecule. It’s composed of three carbon atoms, eight hydrogen atoms and two oxygen atoms, and it’s technically an alcohol.
The first documented description of it comes from the mid-19th century, and in the mid-20th century it started being used in a variety of medicines and other consumer products. PG isn’t very toxic at all, and is “generally recognised as safe” for ingestion.
As well as being non-toxic, PG also has many useful properties. It’s a solvent, a preservative, a moisture-preserver and an emulsifier – which means it helps oily and watery ingredients mix together. It’s especially useful as a solvent, because it mixes with water, alcohols, drugs such as diazepam that can’t be mixed with water and vegetable glycerine.
This wide range of uses, combined with its safety, means that PG is used in many products. It’s used in foods as a preservative and moisture-retainer, and in food colourings and flavourings a solvent. It’s found in deodorants, moisturisers, shampoos and conditioners, suntan lotion, lipsticks and many, many more everyday products.
It’s also used in some specific types of anti-freeze designed to be child and pet-safe. This is because it lowers the freezing point of water much like another chemical commonly used in antifreeze (ethylene glycol) does, but is much less toxic.
Finally, it’s also one of the two main ingredients in e-liquid, alongside VG. The quantity of PG in e-liquid varies, so to find out how much is in your e-liquid, look for the PG/VG ratio. This is usually listed on the bottle.
PG Allergies vs. Sensitivities: What’s the Difference?
Before we discuss allergies and sensitivities to PG, it’s important to make sure we’re using the terms correctly. There’s a lot of confusion about the difference between allergies and sensitivities or intolerances, and you’ll often notice people using the terms interchangeably. But they’re really quite different issues.
The key factor that separates them is your immune system. In an allergy, your body identifies a certain component in a food or something else you’re consuming as a “threat.” Like it does in response to an infection, your immune system responds to the perceived threat by creating antibodies specifically designed to fight it off.
In contrast, sensitivity or intolerance to a chemical is not as clearly-defined, and doesn’t involve the immune system in the way an allergy does.
The most well-known example is lactose intolerance, where some people don’t have the right enzymes to break down the type of sugar found in milk. This leads to problems like bloating and diarrhoea.
However, other sensitivities and intolerances aren’t caused by the lack of an enzyme, and in many cases we don’t really understand the mechanisms involved. The simple fact is that some people react badly to some foods and other substances.
Our Survey: Finding Out About PG Sensitivity and Allergy
We conducted a survey of 1,018 vapers in an attempt to shed more light on the issue of PG sensitivity and allergy.
- how long vapers had been vaping, whether they still smoked
- the symptoms they’ve been experienced
- when the symptoms started
- how long they lasted for
- what changed before the symptoms cleared up (if anything)
- the most PG people can vape without symptoms
- questions about potential allergies or reactions to PG in other forms.
Before we get onto the results of the survey and other research into the issue, we want to be up-front about some limitations to the results.
Firstly, we’re a vaping site, so the people who follow us on social media are more likely to be enthusiastic, longer-term vapers than the average vaper on the street. In fact, about 81 % of people who responded had been vaping for longer than a year, and almost 88 % had quit smoking entirely.
Secondly, and most importantly, we were actively asking about reactions to PG, so people who’ve had a reaction were probably more likely to respond than people who haven’t had one. This doesn’t appear to have been too much of an issue, but it’s one thing to bear in mind as we go over what we found.
Finally, it goes without saying that this is just a survey, so we can’t definitively say that these reactions were due to PG. If someone thinks PG is responsible, that’s what it goes down as.
People probably have a good idea where their symptoms come from, but some will have undoubtedly blamed PG for some symptoms that have nothing to do with it.
PG Allergy: What Are the Symptoms and How Common Is It?
If you’re having a bad reaction to vaping, you should now see that it isn’t necessarily an “allergy.” In fact, the odds are that it’s sensitivity rather than an allergy, but it is possible that you’re having an allergic reaction.
Documented allergic reactions to PG tend to be from skin contact. As mentioned earlier, PG is in so many different products you’ve probably already come into contact with PG on your skin. This means many people will a true PG allergy will probably be well aware of it – or at least that you have an allergy to something – before you start vaping.
If you have a PG allergy, you’ll likely show signs of allergic contact dermatitis.
This is characterised by a rash, possibly with small lumps in the surrounding area or even just a patch of redness. Because PG is inhaled when you vape, this will be around your mouth and nose. It may be accompanied by a burning, stinging sensation.
The big issue is that these symptoms are a lot like what you’d get if your skin was simply irritated by PG. This isn’t a true allergic reaction, but the symptoms are so similar it can be really hard to tell which is which. In fact, this is a big part of the reason researchers aren’t quite sure how common PG allergy is.
To separate the irritant reactions from the allergic reactions, you’d have to find an amount of PG that was small enough to avoid irritant effects, but enough to cause an allergic reaction. Of course, researchers have attempted to do just this, and the best evidence suggests that somewhere between 1.5 and 3.5 % of people have an allergic reaction to PG in this way.
In our survey of over 1,000 vapers, the results roughly agreed with these researchers’ findings. Just under 2.2 % of people who responded had rashes after vaping PG-containing juice, about 3.6 % had pimples or hives, just under 2.6 % experienced burning or stinging sensations and about 3 % had itching sensations.
Other research has come up with similar conclusions. One that’s particularly note-worthy was research conducted by Dr. Konstantinos Farsalinos, and found that 1.8 % of over 19,000 vapers surveyed reported allergic reactions.
We don’t want to blow our own trumpet (OK, maybe we do a little…), but since it agrees with several sources, it looks like our survey was quite close to the true figure. With all things considered, it appears that about 2 % of vapers experience allergy-like symptoms from vaping PG.
The upshot is that if you’ve had bad reactions to moisturisers or other PG-containing cosmetics before, you should keep an eye out for signs of a reaction to vaping. If you’ve identified PG as the likely cause of your allergy, you should avoid PG wherever possible (more on this later).
PG Sensitivity: What Are the Symptoms and How Common Is It?
For most vapers who have a reaction to PG, it will be sensitivity to the chemical rather than an allergy. You might have experienced symptoms similar to those of an allergy from moisturisers or other cosmetics. But for the most part, the difference between inhaling PG and applying it to your skin makes the symptoms distinct.
We don’t have hard figures on this, but Chris Price at E-Cigarette Politics has made some estimates on the basis of the number of relevant posts to vaping forums.
He classifies PG sensitivity into two main groups on the basis of the symptoms you’re likely to experience.
According to Price’s estimates, about 1 in 10 vapers have a slight sensitivity to PG that mainly manifests through a dry throat and slight irritation to the upper airways.
How much of this is a true “sensitivity” is uncertain, because it tends to fade as you get used to vaping (as many studies have found). Some new vapers also experience this because they don’t know that smoking and vaping technique is slightly different, and you have to slightly alter how you inhale to get the most out of it.
The more serious cases of PG sensitivity are estimated to affect 1 in 100 vapers. These individuals will experience a very sore throat when vaping higher-VG juices, and this often makes vaping intolerably unpleasant.
Our survey again roughly agrees with these estimates. The biggest difference is in the estimates of slight sensitivity, with 21.7 % reporting a cough and 27.8 % reporting a sore or dry throat, which is two to three times higher than Price’s estimate.
However, the vast majority of these people didn’t have symptoms for long. Out of these vapers, 39.6 % only had symptoms for less than a week, and 75 % had symptoms for less than a month.
For severe sore throat, about 1.6 % reported experiencing the symptom after vaping. Some of the people who reported a burning or stinging sensation could also have a severe sensitivity, but including these only increases the figure to about 3.8 % of respondents.
Dr. Farsalinos’ study only included an option for “sore or dry mouth and throat,” and 38.9 % of respondents reported this symptom.
Studies of the effectiveness of vaping for quitting smoking often ask about side effects too, and these generally find that 20 to 30 % of vapers get a dry mouth or throat, and about the same percentage report throat irritation. Researchers generally find that side effects from vaping are mild and temporary.
Although there is some agreement between our survey and other sources, this is much less clear-cut than the findings about allergies. It’s just quite difficult to say when it’s mild sensitivity and when it’s the ordinary process of getting used to vaping.
However, the overall message is that many people experience some mild reactions to PG, but these usually clear up. Severe sensitivity is much rarer, affecting about one or two out of every hundred vapers.
PG Sensitivity Among Recent Quitters: Is the PG Really to Blame?
Although it’s entirely possible that new vapers having problems such as sore throats are having a reaction to PG, it’s not the only explanation. In fact, several symptoms often accompany quitting smoking, and these can overlap a little with the symptoms of PG sensitivity or allergy.
Our survey found that 58.8 % of people who developed symptoms first had them within a month of starting to vape, so it’s very possible that some of these were related to quitting smoking rather than starting vaping.
Two symptoms of quitting smoking in particular could mimic signs of PG sensitivity or allergy. Firstly, the “quitter’s flu” involves many cold and flu-like symptoms, including congestion, coughing, sore throat, headaches and more.
If you’re experiencing symptoms like this, you may attribute the coughing, sore throat and headaches in particular to vaping. However, since many quitters get this issue even without vaping, it’s not always easy to point to PG as the culprit.
Similarly, there’s another issue known as “quit zits,” which is basically what it sounds like. Some people develop acne after quitting, although the scientific evidence on this is inconclusive.
It may be that smoking actually reduces your risk of acne, and so quitting appears to make it more likely because the protective effect is removed. Regardless, many quitters report acne breakouts as a symptom, so it’s another thing to bear in mind if you think you may have a PG allergy.
The challenge is determining whether it’s the quitter’s flu or a PG sensitivity, or whether it’s quit zits or an allergic reaction. Generally, allergic skin reactions will be centred around your mouth and nose, whereas a breakout of quit zits won’t be so confined.
Separating quitter’s flu from PG sensitivity may be more difficult, but if you’re experiencing congestion in your airways and headaches alongside a sore throat and coughing, it’s probably to do with quitting smoking rather than starting vaping.
However, it’s still a little complicated. For example, you could have quitter’s flu and be having a reaction to PG. In fact, the effects could combine and make the sore throat even worse. This is another reason it can be hard to pin the blame on one specific thing. The best thing to do is try to avoid PG and see if the condition clears up.
How Long Do PG-Related Symptoms Last?
If you’re having fairly mild symptoms from vaping, you might not be too eager to change how you vape. The question is: can you just put up with the symptoms for a while and hope they’ll go away?
Our survey showed that of the people reporting problems, 44.1 % no longer experience issues, and another 44.8 % only get symptoms every so often, rather than all the time. This only leaves about 11 % experiencing symptoms continuously and never having it clear up.
Similarly, 38.9 % of people who had problems reported that they cleared up within a week, and another 35.1 % had them clear up between a week and a month after they first experienced them. Just under 26 % of people having symptoms, or about 11.8 % of vapers overall had symptoms that lasted longer than a month.
The evidence seems to show that most potentially PG-related problems experienced by vapers clear up quite quickly.
Having ongoing, long-term problems is pretty rare. Only 5.7 % of people who responded had issues for longer than a month that weren’t intermittent, and most of this was coughing or a dry/sore throat.
Dr. Farsalinos’ study found very similar results, with only 5.5 % of the people who experienced symptoms saying that they were completely unresolved at the time of the survey.
Other Issues Possibly Related to PG – Headaches, Tinnitus and More
Although these aren’t as firmly established or consistently reported as other symptoms, it’s important to note that some vapers report other symptoms from PG.
One example comes from a post to the E-Cigarette Forum, where – in addition to acne – the author reports things like tightness in the chest and a feeling of her throat closing up.
Studies looking at people trying to quit smoking by vaping often include headaches as a reported symptom, and there is some discussion on forums and Reddit about the possibility of worsening tinnitus from vaping.
We asked about some of these symptoms too, but in general they were quite rare. Chest tightness was the most common, with 6.1 % of vapers reporting it, and around 6 % reported headaches.
Although headaches could be due to a “quitter’s flu” or a reaction to PG, it seems more likely that dehydration is to blame. PG and VG suck in moisture from their environment, so dry mouth and general dehydration is an expected issue.
Chest tightness could be related to PG, but there are a lot of factors at play here and it’s hard to definitively pin down the cause. Most of the vapers who reported chest tightness had the problem clear up quite quickly, and a couple specifically commented that it was only mild. That said, chest pain is something to take seriously, so if you’re concerned, go to the doctor.
Finally, about 1.8 % of the vapers reported worsening tinnitus after vaping. Hearing problems from vaping got a bit of attention when Pendulum’s Rob Swire blamed vaping for his hearing loss.
However, the evidence on the topic tends to relate to dropping PG directly into the ears, so this might not be so clear-cut. Stimulants in general can make tinnitus worse, so it could be nicotine (or even the caffeine in your tea or coffee) rather than PG too.
Overall, while there are some other things to look out for when you’re vaping, most can’t be clearly linked to PG, so you can’t be certain that switching juices will solve the problem.
Avoiding PG While Vaping
So if you do think your issues are related to PG, what do you do about it?
Well, the obvious answer is to switch to a VG-based e-liquid. These days, VG e-liquids are easy to find, and if anything, most e-juice is predominantly VG. However, there is usually some PG present too, because a pure VG e-juice would have issues with wicking.
Many vapers find that as long as the PG content is kept low, they don’t suffer serious signs of PG sensitivity. This varies, so you’ll have to try some high-VG options out yourself to see how well it works for you.
For example, Element E-Liquid uses 80 % VG for it’s Dripper Series, which is high enough for most PG-sensitive vapers. Alternatively, some companies add a small amount of distilled water to create a completely PG-free e-juice.
There is also a possible alternative to PG in the form of PEG, polyethylene glycol. If you do try this approach, make sure you choose a juice that uses PEG400, and preferably with a lab report confirming that it doesn’t contain diethylene glycol or monoethylene glycol.
Of the people who had problems, 38.1 % said their issues cleared up after switching to a higher-VG juice. But the amount of PG people said they can tolerate varied quite a lot. For example, 26 % of the people who had an answer to the question said that they could have more than 50 % PG without issues. However, 44.2 % said that they could only comfortably vape e-liquids with less than 30 % PG.
If you’ve gone for a much higher-VG e-juice, one of the biggest problems you may face relates to wicking. VG is much thicker than PG, so it isn’t sucked up into your wick as effectively and you may occasionally experience dry hits.
If you’re having this issue, the best advice is to get a sub ohm tank (or rebuildable atomizer), which tend to have better wicking, turn the power down a little and leave longer between puffs. Turning the power down means that less e-juice is vaporised with each puff, so less has to be replenished before you can vape again without dry puffs.
A final issue when you’re switching to high-VG e-juice, especially if you’re just quitting smoking, is throat hit. PG does contribute to the throat hit you get from your setup, and recent switchers in particular are likely to need throat hit to replicate the sensation of smoking.
The best advice is to use a higher-nicotine e-juice, because nicotine contributes the majority of the throat hit anyway. Using menthol-based flavours also boosts throat hit. There are more tips on throat hit in this post.
However, of the people who had problems, another 26.9 % said that reducing nicotine actually helped. This shows that while PG may be causing the problem, it could be the throat hit from nicotine that’s making vaping unpleasant for you.
E-liquid flavorings are also diluted in PG, so you could be having a reaction to the PG in flavorings or the flavoring ingredients themselves. The best advice is to experiment with different juices and see what effect they have.
Sidestepping Your Sensitivity and Avoiding Your Allergy
The bottom line is that while allergies and serious sensitivity are both fairly rare, a lot of vapers have a milder sensitivity to PG. The good news is that avoiding the problem is quite easy.
The good news is that avoiding them is quite easy. As long as you make sure your setup and vaping style are well-suited to more viscous, low-throat hit high-VG e-juices, you’ll be able to transition without problems. If the problems don’t clear up, it could be due to quitting smoking, or even something else entirely.