The ingredient, explained

Proline

A published expert assessment examines cosmetic-use safety.

Hair conditioningSkin conditioning

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Ingredient guide

What it is and what it does

2-Pyrrolidinecarboxylic acid, -S--

About this ingredient: EU CosIng ingredient registry (via Open Beauty Facts taxonomy) ↗

Hair conditioning: Improves cosmetic hair properties such as softness, shine or combability.
Skin conditioning: A broad cosmetic role for maintaining skin condition. It does not identify a particular clinical benefit.

Function definitions: European Commission ingredient function definitions (SCCNFP/0299/00, pages 16 to 20) ↗

Registry functions describe possible formulation roles, not results for a finished product. A dictionary entry is not an approval or a safety assessment.

A closer look

What the research shows

Safety assessment

Proline is explicitly included in the amino-acid group covered by the cosmetic-use safety conclusion.

What this does not tell us

This is an exposure and toxicology assessment. Evidence about a proline derivative or collagen does not establish an isolated topical proline benefit.

Sources for this summary. PubMed 24335967 ↗

Research review checked Oct 1, 2026

Bounded targeted searches for the exact ingredient identity in primary research or final expert assessments, with selected-source verification. Not a systematic review.

Ingredient research is not proof that a product containing this ingredient works.