Glycerine and glycol can be easily confused because they are both odorless, colorless, syrupy and sweet. But that would be a potentially deadly mistake. Glycerine has many purposes, including use as a food sweetener and preservative, but glycol is highly toxic and is used primarily as an antifreeze in vehicles.
Glycerine is more commonly called glycerol, which can add to confusion because of the similarity between the terms "glycerol" and "glycol." Glycerol is a by-product of the production of soap and the refining of vegetable oils and biodiesel fuel. It is a humectant, which means it attracts, absorbs and retains moisture from the air. For this reason it's a popular ingredient in skin lotions. It is used as a natural sweetener, a solvent, a preservative and a thickening agent. The combination of a glycerol molecule and fatty acids produces the triglycerides that make up most of our dietary fats.
Physicians use glycerol to reduce pressure or fluid in the eye. Glycerol is also used to reduce swelling in the brain in patients with increased pressure in the skull or a brain hemorrhage. Glycerol injections are used to treat a condition called trigeminal neuralgia that affects the trigeminal nerve (one of the cranial nerves) and causes sudden, severe facial pain. The glycerol relieves the pain by damaging the trigeminal nerve fibers. In the form of a suppository, glycerol is used to relieve constipation.
Glycol is better known as ethylene glycol. It is a synthetic liquid used to make antifreeze and de-icing solutions for cars, airplanes and boats. It’s also a component of ballpoint pens and hydraulic brake fluids. Ethylene glycol is toxic to humans and animals.
According to the Centers for Disease Control (CDC), ethylene glycol in the air breaks down in about 10 days. If it seeps into water or soil, it breaks down within a few days to a few weeks. The primary way people are exposed to ethylene glycol is by touching or drinking antifreeze. There is also a risk to people who work in industries where they’re exposed to the substance. While it’s very toxic to humans, ethylene glycol may pose an even bigger risk to animals. If it's spilled while antifreeze is being added to a vehicle, animals may drink it eagerly because of its sweet taste.
A tiny amount of ethylene glycol will probably not harm humans, but according to the National Library of Medicine, as little as 4 fl. oz. may be enough to kill an average-sized man. The CDC states it can damage the kidneys, nervous system, lungs and heart. Ethylene glycol affects the body two ways. It can turn into crystals that collect in the kidneys, and it's an acid that affects the nervous system, lungs and heart. Drinking ethylene glycol causes the same feelings as drinking alcohol, but in a few hours the symptoms will turn into nausea, vomiting, convulsions and possibly coma.