But today, with the help of a cosmetic chemist and board-certified dermatologist, we're going to be talking about dipropylene glycol for hair (DPG for short), an ingredient that sounds complicated and alarming, but is actually quite harmless. Read on to get all the details on dipropylene glycol, below.
Meet the Expert
- Kelly Dobos is a cosmetic chemist and adjunct professor at The University of Toledo.
- Anna Guanche, MD, is a board-certified dermatologist, celebrity beauty expert, founder of Bella Skin Institute in Calabasas, CA.
- Type of ingredient: Humectant and product stabilizer
- Main benefits: Helps stabilize haircare products, can act as humectant, helps dissolve extracts and preservatives
- Who should use it: Dipropylene glycol can be used with all hair types.
- How often can you use it: It can be used daily.
- Dont use with: "There is limited evidence on ingredients that react well with dipropylene glycol and those that hinder its effectiveness and increase toxicity," explains Guanche.
Benefits of Dipropylene Glycol for Hair
Dipropylene glycol doesn't necessarily have a ton of benefits for hair, but it does help with product formulation. It's non-toxic, odorless and is used in products including shampoos, conditioners and styling products.
- Can act as a humectant: Guanche says it "helps retain and absorb moisture in the hair. It does not evaporate, mitigating dry and brittle hair."
- Acts as a thickening agent: Guanche notes that DPG acts as a thickening agent that can help protect and strengthen the hair shaft.
- Product stabilizer: "It allows for the longevity of skincare products and ability to transport across different regions of the country and world without having product freeze and thaw, which can spoil it," says Guanche.
- Improves product texture: Dipropylene glycol can help thin out a product texture to give it a more silky, sleek feeling.
- Can mask scents: If you're not down with scented products, you'll be happy to know that this ingredient works to hide the scent of other ingredients, giving your product that "unscented" scent.
Hair Type Considerations
All hair types can use products formulated with dipropylene glycol. Dobos explains, "The Cosmetic Ingredient Review's expert panel made up of medical professionals, toxicologists, and other scientists determine DPG is safe in their review of extensive data about the use of DPG at concentrations of up to 50% in cosmetics and determined."
In some cases, the ingredient can cause allergic reactions. "Although products with dipropylene glycol have been found to be safe for sensitive skin types and thinner hair, it is always advised to take precaution if one is allergy prone," says Guanche. "Many are allergic to propylene glycol, and some are allergic to DPG as well. Often, they will assume they are allergic to fragrance, but it is actually the DPG in some cases. Luckily, this allergy is relatively rare, considering the number of products that contain this ingredient. Propylene glycol differs from dipropylene glycol in that it only has two alcohol isomer groups, contributing to its ability to dehydrate the hair and cause scalp irritation."
How to Use Dipropylene Glycol for Hair
As mentioned, dipropylene glycol is used in a wide array of haircare products, including shampoos, conditioners, styling products, and even coloring products. It's not necessarily a selling point in haircare products though. (In other words, if it's not in a product, you're not missing out on any direct benefits to your strands.)
There isn't one specific way to use it (if it's in your shampoo, great!) and you don't have to worry about over-doing it. Dobos reiterates that this ingredient is safe for all skin and hair types.
Dipropylene glycol is not dangerous at all. It has been ruled safe to use in cosmetics by the FDA as well as the The Cosmetic Ingredient Review's expert panel.
You might have heard of DPG's friend propylene glycol and are wondering if there is a difference. Propylene glycol is derived from petroleum and also acts as a humectant and preservative. However, studies have shown that propylene glycol can be irritating to the skin and scalp .
Andersen KE, Storrs FJ. [Skin irritation caused by propylene glycols]. Hautarzt. 1982;33(1): 12-14.