Ferment Filtrates / Lysates / Inactivated Probiotics
The beneficial by-products of microbial fermentation — and the inactivated microbes themselves — used in skincare to support the skin's microbiome without the instability of live bacteria. In practice this means ferment filtrates (the liquid left after culturing a microbe), lysates (broken-down bacterial fragments), and the metabolites they leave behind: short-chain fatty acids, peptides, organic acids and enzymes. Because they don't need to stay alive, postbiotics survive preservation and shelf life far better than true live probiotics — which is why most "probiotic" skincare on the market is, technically, postbiotic. Galactomyces and Lactobacillus ferments are the everyday examples.
Postbiotics are a class, not a single measured active. Ferment filtrates and lysates often sit near the top of the INCI list because the ferment liquid is much of the base — so list position tells you little. What matters is the specific, characterised ferment (which strain, cultured how), not a percentage; standardisation between brands is poor, so judge the ingredient, not its rank.
Layer like any hydrating or soothing step — after cleansing, before heavier creams, AM and/or PM. Postbiotics are among the gentlest microbiome actives and pair comfortably with niacinamide, hyaluronic acid, and barrier lipids, with no meaningful conflicts against actives like retinoids or acids. Ferment-derived ingredients sensitise a small minority of people, so patch test first if your skin is reactive.
Build a routine using Skin Stacker's free AI-powered tool — decode any product, check ingredient compatibility, and get a personalised AM/PM schedule.
Open Skin Stacker →