PROPYLENE - Skin Care Ingredients Curated By Mia Seilern

By KimReviewed Nataly

⚠️ Data is provided for informational purposes only. It may contain inaccuracies and should be independently verified. This is not medical advice. Consult a healthcare professional before making health decisions.

Description: PROPYLENE — PROPYLENE. Formula: C3H6. MW: 42.08. IUPAC: prop-1-ene.

Quick Facts:

Category: other
Also Known As: Propylene

Proven Benefits At A Glance:

Propylene glycol is a widely used ingredient in cosmetics, medications, and personal care products as a solvent and emollient
It can cause both irritant and allergic contact dermatitis in some people
Propylene glycol was named Allergen of the Year in 2018 by the American Contact Dermatitis Society
It is considered a weak allergen, and allergic reactions are uncommon in people without pre-existing skin conditions
At very high doses or with prolonged use, propylene glycol can cause systemic toxicity, though this is rare in typical skincare use

Safety: Generally Low ConcernResearch confidence: None

Safety tier is a starting heuristic from regulatory status and comedogenic rating, not a dermatological verdict — see our Terms for the full disclaimer. Research confidence reflects how many real cited studies back this ingredient, not the strength of their findings.

🧪 PROPYLENE

PROPYLENE

CAS Number: 115-07-1

Also Known As: Propylene

Category: other

PROPYLENE. Formula: C3H6. MW: 42.08. IUPAC: prop-1-ene

PROPYLENE is an other ingredient used in skincare formulations.

🌍 Regulatory Status

EU: No restriction on fileUS: No restriction on file

📊 Comedogenicity

No data yet

Not rated for this ingredient yet.

📚 Research & Evidence

PUBMED CITATIONS

Data sources: EU CosIng PubMed

🔬 The Science

Propylene glycol (PG) is a small-molecule solvent that serves multiple functions in skincare and pharmaceutical formulations—it dissolves active ingredients, helps products absorb into skin, and maintains moisture. Despite its widespread use, PG has a complicated safety profile. #1: Contact dermatitis risk — Propylene glycol can trigger two different skin reactions (Dermatitis, 2018; J Am Acad Dermatol, 1991). Some people experience irritant contact dermatitis, which is a direct inflammatory response to the ingredient itself. Others develop allergic contact dermatitis, where the immune system reacts to PG as a foreign substance. The distinction matters because PG acts as both a weak sensitizer and an irritant, which can make patch testing results confusing for dermatologists trying to diagnose sensitivity (Dermatitis, 2018).

#2: Allergen status and prevalence — While PG has the potential to be a weak allergen, allergic reactions to it are relatively uncommon in people without underlying skin conditions (Regul Toxicol Pharmacol, 2023). Interestingly, this creates a scientific puzzle: propylene glycol fails to trigger sensitization in standard laboratory tests (guinea pig models, mouse models, and validated in vitro tests) yet does cause allergic contact dermatitis in some real-world human cases (Regul Toxicol Pharmacol, 2023). The ingredient is not classified as hazardous under global chemical classification systems, yet awareness of PG sensitization has grown enough that the American Contact Dermatitis Society highlighted it as their 2018 Allergen of the Year (Dermatitis, 2018).

#3: Systemic toxicity at high doses — In typical skincare concentrations, propylene glycol is considered safe for most people. However, when used in very high doses or over prolonged periods, PG can accumulate in the body and cause systemic toxicity (J Pediatr Pharmacol Ther, 2014). Documented adverse effects include central nervous system effects, cardiac arrhythmia, seizures, and lactic acidosis. Certain populations are at higher risk: infants, people with kidney or liver problems, those with epilepsy, and burn patients receiving extensive dermal applications of PG-containing products (J Pediatr Pharmacol Ther, 2014). This risk is relevant mainly to medical and pharmaceutical uses rather than cosmetic skincare.