What it is
Methylpropanediol is 2-methyl-1,3-propanediol, a colorless, viscous liquid belonging to the glycol family. In formulas it dissolves other ingredients, helps hydrate skin while leaving a non-sticky finish, and is often used as an alternative to glycols such as propylene glycol or butylene glycol. It also has useful antimicrobial activity, so it is frequently added to strengthen a product's preservative system rather than to act as the sole preservative.
Safety & warnings
As a small, water-miscible glycol used at modest levels as a solvent and humectant, methylpropanediol is generally considered well tolerated and is positioned in industry literature as a gentler-feeling replacement for older glycols. Because glycols can act as penetration enhancers and a small number of people are sensitive to this ingredient class, those with very reactive or compromised skin may wish to patch test products that list it high in the ingredients.
Questions everyone asks
Why is methylpropanediol in my sunscreen?
It works mainly as a solvent and humectant, helping dissolve other ingredients and draw in moisture for a non-sticky feel. It also boosts the preservative system, helping keep the formula stable.
Is methylpropanediol the same as propylene glycol?
No, but it is a related glycol. It is 2-methyl-1,3-propanediol and is often used as an alternative to glycols like propylene glycol or butylene glycol, with a comparable solvent and humectant role.
Is methylpropanediol a preservative?
Not on its own. It has antimicrobial properties and is commonly used as a preservative booster, meaning it supports and strengthens the main preservatives in a formula.