Humectant
Pronunciation: hyoo-MEK-tant
A hygroscopic substance that draws water from the dermis into the epidermis and from the environment into the skin to increase skin hydration.
Full Definition
Humectants are hydrophilic molecules that attract and bind water, functioning through hydrogen bonding to increase the water content of the stratum corneum. Common cosmetic dermatology humectants include hyaluronic acid (in topical, not injected, form), glycerin, urea, and panthenol. In arid climates or low-humidity environments, humectants may paradoxically draw water from deeper skin layers, exacerbating dryness; editors of patient-facing content should be aware that unqualified claims about humectant efficacy may not hold across all conditions. The term is frequently encountered in ingredient function tables, formulation briefs, and clinical study protocols.
Usage
Usage note: Distinguish carefully from 'emollient' and 'occlusive' in ingredient function tables. Note that hyaluronic acid functions as a humectant when applied topically, unlike its injectable filler role.
In Context
- "Glycerin, acting as a humectant, was included at 5% to maintain epidermal hydration between treatment sessions." — Formulation rationale document
- "The patient brochure incorrectly described the product's hyaluronic acid as a filler ingredient; in topical use it functions as a humectant." — Editorial correction note