Bacillus/Folic Acid Ferment Filtrate Extract

Bacillus/folic acid ferment filtrate extract is typically used at low concentrations as a skin-conditioning/soothing ferment-derived ingredient, and folate itself is not a common primary irritant. However, ferments are biologically complex mixtures and can trigger irritation or rare sensitization in highly reactive or eczema-prone patients, especially when the barrier is compromised. Overall it is generally well-tolerated but not inert, warranting a gentle (not exceptionally gentle) score for patient safety. Safety Notes: In commercial skincare, Bacillus-based ferment filtrate extracts (including folic-acid–fermented variants) are commonly used at very low levels as marketing/skin-conditioning actives, with many leave-on serums/creams and toners incorporating them around ~0.01–0.1% (often due to supplier-recommended use levels and because the ingredient is frequently supplied in diluted carrier solutions). Higher-strength consumer products marketed as “ferment/biome” concentrates can reach ~1–5% for leave-on applications, especially when the filtrate is used as a featured active or when multiple ferments are stacked; rinse-off products typically sit toward the low end because contact time is brief. No specific OTC maximum is set by FDA/EU for this INCI name, so the practical upper bound is driven by stability, odor/color, and preservative compatibility rather than a hard regulatory cap.