Panthenol (pro-vitamin B5)
One of the few genuinely uncontroversial actives: humectant, barrier support and soothing, with a real conversion mechanism and almost no downside.
What is panthenol?
Panthenol is the alcohol analogue of pantothenic acid, vitamin B5. It is converted to pantothenic acid in skin, which is a precursor of coenzyme A and therefore involved in lipid synthesis — the mechanistic basis for its barrier effects. It is used as D-panthenol (dexpanthenol), the biologically active enantiomer, or as a racemic mixture.
What it does
Three things, all reasonably supported. It is a humectant, holding water in the stratum corneum. It supports barrier lipid synthesis via the coenzyme A pathway, with measurable effects on transepidermal water loss. And it has anti-inflammatory and wound-healing activity, which is why dexpanthenol is used in medical topical preparations for minor wounds and irritated skin.
That combination — hydration, barrier and soothing, with a plausible mechanism for each — makes it one of the more reliable ingredients in cosmetic use.
Levels
Cosmetic use typically runs 0.5% to 5%, with medical preparations higher. Youlief uses it at up to 0.075% across five products, which is below the range at which the barrier and wound-healing work was done — a supporting rather than a starring role. Vegalab uses it in the Scalp Repair NanoSerum, Bio-Ferment toner and Soothing Recovery Gel.
What does panthenol not do?
It is not an anti-aging active, not a pigmentation active and not an exfoliant. Its virtue is reliability in a supporting role, not dramatic effect.
Is panthenol safe?
Very well tolerated, including on compromised skin, with a low sensitisation rate. One of the safer choices for reactive skin.