Propanediol Explained

Butylene glycol · 1,3-propanediol · Glycols

Propanediol and butylene glycol are gentle moisturising solvents that help other ingredients absorb; they are well-studied and safe.

Evidence: strong

Label names (INCI): Propanediol, Butylene Glycol, Pentylene Glycol, Dipropylene Glycol, Propylene Glycol

Written by the Oliareen editorial teamDermatologist review: pendingHow we write

What it does

Gentle moisturising solvents that dissolve actives, help them absorb and boost preservatives.

Often discussed for

This doesn't mean everyone with these needs it.

Concerns

Dryness and skin barrier

Skin types

How to approach it

If you're new to it

Start one new product at a time and patch test first: a little on the side of the jaw for a few days. Keep the rest of the routine simple.

General education, not a diagnosis or treatment plan.

Works well with

Examples of common pairings, not guaranteed combinations.

Fits most routines

Use carefully with

Stacking several actives raises the risk of irritation. If you're on any prescribed medicine, ask your doctor before adding an active.

Propylene glycol is an uncommon contact allergen; butylene glycol/propanediol rarely
Safe in pregnancy

Possible reactions

Stop if burning doesn't settle, or if you get a red rash, itching, swelling or peeling. Swelling of the face, lips or eyes, or trouble breathing, needs urgent medical care.

When to see a doctor

Evidence and timing

Evidence: Evidence: strong
Time to see a change (weeks): n/a

Evidence comes from studies of specific formulas and strengths. Your product may behave differently.

Sources

CIR Butylene Glycol et al. J Am Coll Toxicol 1985;4(5):223-48 (safe as used)
CIR 2018 Alkane Diols incl. Propanediol
CIR Propylene Glycol amended 2012