Butylene Glycol vs Glycerin: which is worse?

What is Butylene Glycol?

Butylene glycol (1,3-butanediol) is a small diol used in cosmetics as a humectant, solvent, and skin-conditioning agent. It is closely related to propylene glycol but has a slightly larger molecular structure, often making it even better tolerated.

What is Glycerin?

Glycerin is a simple polyol (sugar alcohol) that is colorless, odorless, and viscous. It naturally occurs in all animal and vegetable fats and is the backbone of triglyceride molecules. Cosmetic glycerin is typically derived from vegetable oils (plant-based) or as a biodiesel byproduct.

Documented risks

Butylene Glycol: Butylene glycol has a good safety profile and is better tolerated by sensitive skin than propylene glycol at equivalent concentrations. The CIR has confirmed it safe for cosmetic use. It is non-carcinogenic, non-mutagenic, and not an endocrine disruptor. Contact sensitization is rare. It is widely used in Korean beauty (K-beauty) formulations as a preferred humectant.

Glycerin: Glycerin is one of the safest cosmetic ingredients known, with centuries of use. The CIR has repeatedly confirmed its safety. It is non-irritating, non-allergenic, and non-toxic. At very high concentrations in leave-on products (>30%), it can have a dehydrating paradox effect — pulling water from the dermis if the environment is very dry — but this is not a health risk. It is safe for all ages including infants.