What is the difference between Propylene Glycol (PG) and Vegetable Glycerin (VG)? Is e-juice/e-liquid safe or harmful? What are allergies and side effects of e-juice/e-liquid? E-cig e-juice also called e-liquid is made with a mixture of propylene glycol (PG), vegetable glycerin (VG), flavoring, and nicotine. Occasionally water or a sweetener is added. The percentage of PG to VG varies by brand. Difference Between PG vs VG Vegetable glycerin is thicker than propylene glycol. Ejuice with more of VG will generate more vapor. Ejuice with more PG carriers the flavor a lot better and delivers a greater throat hit. You can also get 50PG/50VG ejuice to balance the two. Ejuice Safe or Harmful? Both PG and VG are used in food, medical and pharmaceutical products. Asthma inhalers actually use PG as well. PG is generally recognized as safe (G.R.A.S.) by the FDA. Source: http://www.accessdata.fda.gov/scripts/fcn/fcnDetailNavigation.cfm?rpt=scogslisting&id=262 Some assume that propylene glycol is harmful because it's used in anti-freeze. The fact is it's used as a safer alternative for ethylene glycol to make non-toxic anti-freeze. Allergies and Side Effects of Ejuice You would likely know if you're allergic to ejuice since a lot of consumables are made with these ingredients. Allergy symptoms of PG include eczema, throat irritations, and nausea. Switching to 100% VG should resolve these symptoms. Side effects for PG and VG include dry mouth, sore throat, and increased thirst, which all can be cured by just drinking more water. The symptoms are usually just seen when just starting out vaping. Sometimes symptoms of switching from tobacco cigarettes to ecigs can be confused with ejuice side effects, but are actually withdraw from quitting cigarettes.