Research is starting to give us an idea about the safety or harm of vaping. Some brands may be safe, but some may include known irritants to the lungs.

Article at a Glance:

  • Vegetable glycerin is the base of many e-liquids used for vaping.
  • Vegetable glycerin is a colorless or brown liquid that is sweet-tasting.
  • Vape fluid also commonly contains nicotine, flavorings, and colorings.
  • Vegetable glycerin has not been thoroughly tested for safety.
  • The Recovery Village can help people addicted to e-cigarettes.

E-cigarettes are battery-operated devices that heat fluid into a vapor that is then inhaled. The vapor fluid, also known as e-liquid, usually contains flavoring. However, it may also contain drugs of abuse such as nicotine or tetrahydrocannabinol (THC).

Propylene glycol and vegetable glycerin are the most common base fluids, but e-liquid sometimes contains a combination of the two. A 2017 study on e-cigarette flavors reported that there were more than 7,700 commercially available e-liquids at the time, and the flavorings had not been evaluated for toxicity when inhaled.

Most e-liquids are made with a combination of flavorings, nicotine or THC and a base fluid-like vegetable glycerin. Vape fluid can also contain any number of unlisted ingredients.

While the flavorings are generally recognized as safe for oral consumption by the Food and Drug Administration (FDA), some of the ingredients are known to cause irreversible lung damage. These include:

  • 2,3-Pentanedione: Caramel, cream or cheese flavor
  • Acetoin: Butter flavor
  • Cinnamaldehyde: Cinnamon flavor
  • Diacetyl: Butter or butterscotch flavor
  • Vanillin: Vanilla flavors

These ingredients are safe in food or drinks but cause damage to lung tissue when inhaled. Many of the flavoring agents in e-liquids have been banned from inclusion in cigarettes because of their known harm. So far, the FDA has very few regulations regarding e-cigarettes and e-liquid.

Chemicals Used in E-Liquids

Vegetable glycerin acts as the base of many e-liquids, but the base contains many other ingredients. Some of the most common chemicals in vape fluid include nicotine, flavorings, and colorings.


A majority of e-liquids contain nicotine. Nicotine is the primary addictive ingredient in tobacco and is known to encourage addiction and abuse.

Many studies have found that manufacturers often list nicotine levels incorrectly in e-cigarettes, making the amount of consumption hard to gauge. Worse, some “nicotine-free” brands of e-liquid actually do contain measurable levels of nicotine.


The flavorings used in e-cigarettes are mostly food-grade flavorings. These are considered safe to consume by mouth, but we do not have research that confirms the flavorings are safe to inhale. In fact, many are known to cause damage if inhaled. One study suggests that flavorings in e-cigarettes can even alter lung function by preventing cells from healing and dividing.

Diacetyl, an ingredient that provides butter flavoring, has been shown to cause a lung disease called bronchiolitis obliterans (BO). BO happens when the small airways in the lungs become inflamed and prevent the exchange of oxygen and carbon dioxide. BO has the nickname “popcorn lung” because the disease is common amongst workers in plants that produce popcorn and popcorn flavoring.

Cinnamaldehyde is another common flavoring ingredient, but it is a known carcinogen (cancer-causing agent) and skin irritant.


Like flavorings in e-cigarettes, colorings are usually food-grade coloring. Titanium dioxide is a widely used food coloring, which is safe to eat. However, a recent study showed it can cause lung injury when inhaled by mice. For people who vape, avoiding e-liquids with food coloring is the safest option until more information is available on the topic.

What Is Vegetable Glycerin?

Vegetable glycerin, also called glycerol, is a colorless or brownish liquid that is odorless, sweet-tasting and found naturally in some living organisms. Glycerin is used in many industries, including:

  • Food industry: Used as a sweetener, thickening agent or preservative in foods
  • Pharmaceutical industry: Used in the preparation of drug formulations
  • Beauty industry: Used in skincare products, hair care products, soaps and more
  • Medical industry: Used as an over-the-counter (OTC) laxative or as an eye moisturizer

Vegetable glycerin has not been directly linked to toxicity in humans, but several studies have linked inhalation of glycerol to toxic effects in animals.

Summary — Is Vegetable Glycerin Safe to Vape?

Unfortunately, it is difficult to say whether vegetable glycerin is safe to inhale. Here are some things to keep in mind about e-liquid and e-cigarette safety:

  • While vegetable glycerin is considered to be safe for eating, drinking or applying to the skin, it has not been thoroughly assessed for safety in smoking or vaping.
  • Flavorings and colorings are usually food-grade, but there is not enough research to determine if these are safe to inhale.
  • The Flavor and Extract Manufacturers Association (FEMA) has found that over 1,000 flavorings are potentially hazardous to the lungs.

The information shows that inhaling glycerol might have no effect, but it may also have a risk of harm. Researchers have enough evidence to show that inhaling glycerol is probably not safe, but they don’t know for sure if it’s harmful yet.

If you or someone you know is addicted to e-cigarettes or any addictive substance, The Recovery Village is here to help. Contact us today to speak with a representative and learn more about addiction treatment and services. 

Related Topic: How to quit vaping

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Editor – Jonathan Strum
Jonathan Strum graduated from the University of Nebraska Omaha with a Bachelor's in Communication in 2017 and has been writing professionally ever since. Read more
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Medically Reviewed By – Dr. Conor Sheehy, PharmD, BCPS, CACP
Dr. Sheehy completed his BS in Molecular Biology at the University of Idaho and went on to complete his Doctor of Pharmacy (PharmD) at the University of Washington in Seattle. Read more

Canistro, Donatella; et al. “E-Cigarettes Induce Toxicological Effect[…]ise the Cancer Risk.” May 2017. Accessed July 26. 2019.

Chen, Huei-Wen; et al. “Titanium Dioxide Nanoparticles Induce Emphysema-Like Lung Injury in Mice.” The FASEB Journal, 2018. Accessed July 26, 2019.

Clapp, Phillip W.; et al. “Flavored E-Cigarette Liquids and Cinnama[…]mmune Cell Function.” American Journal of Physiology-Lung Cellular and Molecular Physiology, 2017. Accessed July 26, 2019.

Lechasseur, Ariane; et al. “Exposure to Electronic Cigarette Vapors […]lecular Clock Genes.” Physiological Reports, 2017. Accessed July 26, 2019.

PubChem. “Cinnamaldehyde.” 2019. Accessed July 26, 2019.

PubChem. “Glycerol.” 2019. Accessed July 26, 2019.

Medical Disclaimer

The Recovery Village aims to improve the quality of life for people struggling with substance use or mental health disorder with fact-based content about the nature of behavioral health conditions, treatment options and their related outcomes. We publish material that is researched, cited, edited and reviewed by licensed medical professionals. The information we provide is not intended to be a substitute for professional medical advice, diagnosis or treatment. It should not be used in place of the advice of your physician or other qualified healthcare providers.