Home Vaping Health Evidence The Final Word on Propylene Glycol vs. Polyethylene Glycol

The Final Word on Propylene Glycol vs. Polyethylene Glycol



I keep reading warnings, many by the uneducated masses of parrots populating the green face of the Earth and some by the supposedly educated, medical professionals of the world, which impress upon those being warned that the liquid used in E-cigarettes is also used in antifreeze, making it extremely toxic to human beings… and animals, too, allegedly.  The truth, of course, is both more complicated and simpler than the lies and misconceptions surrounding this volatile, semi-political topic based on the rising popularity of electronic cigarettes, purported to be a healthy alternative to “real” (analog) tobacco products.  This antifreeze scare is nothing new.  The most vehement of the anti-smoking gang (the ones who think anything cylindrical, brought to the mouth on a regular basis is a gateway drug to Marlboro Reds) immediately leapt upon the jugular of the first E-cigarettes to hit the First World and disected their ingredients until they found something, anything, that could be used to demonize them to the public who, ironically, were looking for a different way to quit smoking.  They found that one of the main ingredients in E-liquid was polyethylene glycol, which is used in antifreeze and is fairly toxic to humans in large quantities.  The E-cigarette industry answered by changing that ingredient to propylene glycol, a much safer alternative.  In fact, although propylene glycol (or PG) is used in antifreeze as well, it’s only used in RV and Marine antifreeze, colored pink to designate it’s non-toxic qualities.  Hence the picture above.

Here are a few facts about polyethylene glycol (the somewhat dangerous one):

  • Polyethylene glycol is, in fact, used in antifreeze because it lowers the freezing temperature of water.  It produces ethylene glycol when processed.
  • Ethylene Glycol has been known to be lethal in doses as low as 786 mg/kg.  Even the electronic cigarettes that DO utilize polyethylene glycol (PEG) come nowhere near this mark.
  • Laboratory studies on the inhalation of vaporized/aerosolized PEG all showed that inahlation did not, in fact, deliver lethal, or even harmful, doses of PEG to laboratory animals.
  • Antifreeze which uses PEG to lower the freezing point of water is generally dyed a blue/green color (we’ve all seen it on our driveway at one point or another) to indicate toxicity and danger.
  • When ingested (swallowed, not inhaled) PEG is metabolised first into glycolic acid, then into oxalic acid… which is dangerous.  This danger is present in PEG, but as stated above, not enough to cause harm when vaporized.

In contrast, here are some interesting points concerning propylene glycol (the harmless one):

  • PG is metabolised by the human body into chemicals that are naturally occurring in normal, human metabolic functions.  The resulting chemicals are pyruvic and lactic acids, both of which are quite normal in our bodies.
  • PG is listed by the Food and Drug Administration (Yeah, that’s right.  The FDA, otherwise known as the opponents to the E-cigarette industry) as GRAS (Generally Recognized as Safe).
  • PG is present in some antifreeze products, but is colored pink to make it readily recognizable as non-toxic.  This type of antifreeze is often found in boats and RVs.
  • In addition to being approved for human consumption by the FDA, PG is also approved for human inhalation by the Environmental Protection Agency (EPA).
  • Last but not least in the slightest, PG’s germicidal properties has been found to promote healthier human lung function by killing many of the germs and bacteria which take root in the lungs and make us sick with respiratory illnesses.  So, in short, PG is not only harmless, it also induces a state of increased healthiness.

PG is now used by the vast majority of E-juice manufacturers.  PEG was all-but-abandoned when all of this hogwash about antifreeze started causing the sheeple to panic, as they are wont to do whenever they read a headline with the form “Is _____ Really Healthy?”  As you can see by the above-mentioned evidence and scientific analyses, Neither PEG nor PG are actually unhealthy when inhaled.  Of the two, PG is slightly better, which is why most of the E-cigarette industry has switched from PEG to PG.  Of course, they also did so in an effort to shut the ANTZ (Anti-Nicotine and Tobacco Zealots) up… a move which ultimately failed because they have abandoned all attention to scientific evidence in exchange for a vendetta against the industry as a whole.

Please feel free to spread this around to all the skeptics you know.  Encourage them to do more research on their own, and at the very least to read through the sources listed below.  All I ask is that you give ejuiceconnoisseur.com credit as author.  Good luck and VAPE ON!!!!


Propylene Glycol- Wikipedia

Code of Federal Regulations

Product Safety Assessment- Propylene Glycol

Ethylene Glycol Toxicity

Ethylene Glycol- Wikipedia

Are Electronic Cigarettes Safe?

A Germ-Killing Vapor

Deposition and Fate of Inhaled Ethylene Glycol Vapor and Condensation Aerosol in the Rat

Two-week aerosol inhalation study on polyethylene glycol (PEG) 3350 in F-344 rats.


    • Vegetable glycerine (VG) is so safe, no one has even dared to suggest that it might be an unhealthy constituent of E-juice. In reality, however, Propylene Glycol isn’t any less healthy than VG, but because of its scary sounding “other uses,” it raises a bit of controversy amidst people who only read the headlines/titles of articles/theses.

  1. Even this post is pretty full of mis-information. Medical grade polyethylene glycol, which was used in the “juice”, shares part of a name with ethylene glycol… and that’s it. They are, in fact, two different chemical compounds with the poly signifying the fact that it is a polymer.

    Polyethylene glycol is used in a wide variety of medical applications and is completely safe. It is used in things such as eye drops, laxatives, liquid capsules, oral liquids, ointment bases etc. It has also been shown to greatly increase the rate of nerve repair in things such as spinal injuries, though further research needs to be conducted before this application is widely accepted.

    It is not, in fact, used in any anti-freeze.

    The companies simply decided it was easier to change to a different, and actually inferior, compound than to explain to the masses the benefits and differences between “anti-freeze” and polyethylene glycol.

    • Also, the study above mentions PEG 3500 for the substance used in the rat lab study. This is more than 8 times “heavier” than the PEG400 which is/was the standard in the vaporizer industry, meaning that the effects of PEG400 are actually significantly less than even the minimal effects of PEG3500.

    • That was a well-structured, thorough, and expertly argued retort there, buddy. I bow to your superiority. Oh, and I took your advice. Turns out the Propylene Glycol did no measurable damage to my colon or lower intestinal tract. I should take another reading in a few years just to be sure, though, right?

  2. Your info is grossly misleading and wrong regarding PEG. PEG and Ethylene Glycol are different substances. Please keep your facts straight. Ethylene Glycol is antifreeze and PEG is a polymer used in pharmaceutical injectables and medical inhalers. Do some homework prior to spreading propaganda.

    • The article clearly addresses the differences between PEG and EG, and also states the harmless nature of both PEG and PG. What I was pointing out was that despite PEG NOT BEING DANGEROUS, the E-cig industry switched to PG just to placate the worry-warts out there. I put quite a bit of research into this subject before writing it, and the sources are clearly presented at the bottom of the article. Not only that, but I fact check the sources’ sources as well.

      • You still have at least one hugely inaccurate statement in your article which, oddly enough, is the same misunderstanding which started this whole anitfreeze debate to begin with.

        “Polyethylene glycol is, in fact, used in antifreeze because it lowers the freezing temperature of water. It produces ethylene glycol when processed.”

        Ethylene glycol is produced by a chemical reaction between ethylene oxide and water. PEG is never a part of the process.

  3. Thanks for your article, Oliver. I am a vaper myself and consider this technology one of the most effective means of tobacco cessation known to man. That being said, I came across a study done in the last 12 months on the ‘base’ solutions in e-juice, specifically PG, VG, and PEG. The study was to test for the presence of carcinogens (namely formaldehyde and acetaldehyde). The results were not particularly promising for the industry (as these chemicals did show up, especially at high-voltages), but one caveat did stick out. A mixture of basically 40% PEG, 30% PG, and 15% VG showed absolutely ZERO presence of the carcinogenic chemicals.

    Study: http://ntr.oxfordjournals.org/content/early/2014/05/14/ntr.ntu078.full
    Results: http://ntr.oxfordjournals.org/content/early/2014/05/14/ntr.ntu078/T2.expansion.html
    e-Juices Used: http://ntr.oxfordjournals.org/content/early/2014/05/14/ntr.ntu078/T1.expansion.html