Glycerin Allergy Threshold

Glycerin is the backbone that connects three glyceride molecules, but separates during processing. Many consumer products, such as soaps, lotions and shampoos, contain glycerin or a derivative of glycerin. Some foods also contain glycerin. While it is not common to have a reaction to glycerin, some people might break out in a rash or have another type of reaction. Talk with your physician about conducting an allergy test to determine whether you have an allergy to glycerin.


Glycerin is a colorless, odorless thick liquid. It is non-toxic and generally safe to use. While it is commonly used in topical formulas and products, it can also be used as a type of sweetener or preservative in food products. As a sweetener, glycerin is about 60 percent as sweet as sugar, according to a webpage on the University of Idaho website 1. Glycerin is often an ingredient in mouthwash and toothpaste to add a sweet flavor.

Determining Thresholds

Determining a threshold for glycerin involves testing to see at what point glycerin begins causing symptoms. The Food and Drug Administration uses several approaches when determining allergenic thresholds. For example, researchers may conduct analytical processes to figure out sensitivities to glycerin. This process allows manufacturers of consumer products to determine how much glycerin, or other allergen, they can safely have in their product. Another approach to determine a glycerin threshold is collecting data from persons who have had adverse reactions to the substance. Having several complaints about a particular product may force the FDA to evaluate the product to determine causes of the problem. If glycerin is the cause of negative issues, the manufacturer might have to pull the products and re-evaluate the safe level of glycerin.

Allergic Reactions

Your doctor can conduct a skin prick test to determine your threshold for glycerin. The skin prick test, usually conducted on your forearm, exposes your skin to a series of common allergens. Your health-care provider pricks your skin with a tiny needle and applies a series of high-allergenic drops. Since glycerin is mild and non-toxic, you should not have any reactions to it during your skin test. If you do have a rash or other type of reaction to glycerin, you might have sensitive skin, according to Your doctor will evaluate your skin reaction to determine if glycerin is safe for you.

Additional Information

Glycerin can be hidden in your food or personal care products under a different name. If your physician determines you have a low tolerance or threshold for glycerin, avoid products containing glycerine, glyceritol or glycyl alcohol. An allergic reaction to glycerin might cause a mild rash or swelling, but if taken internally, you might have more severe symptoms. If you are suffering from an allergic reaction, contact poison control immediately or head to the emergency room.