Ascophyllum Nodosum

Ascophyllum nodosum (brown seaweed) is typically used as a soothing/humectant antioxidant extract in low concentrations, and standard patch-test data and consumer experience generally show good tolerability. However, botanical extracts can contain variable bioactives and trace iodine/sea-derived contaminants that occasionally trigger stinging or dermatitis in highly reactive or eczematous patients. Given this variability and the sensitive-skin population focus, it merits a gentle-but-not-inert score. Safety Notes: Ascophyllum nodosum (typically used as an extract/ferment/seaweed bioactive rather than whole algae) is often included at very low levels in mass-market moisturizers, toners, and shampoos where it functions mainly as a marketing/antioxidant-conditioning adjunct, with practical in-formula use commonly starting around 0.01–0.5%. High-strength consumer products (marine/seaweed serums, masks, and concentrated “algae extract” ampoules) can reach ~1–5% active or equivalent extract solids, especially in leave-on products; rinse-off products generally sit lower due to cost and deposition limits. There is no specific EU/FDA maximum for this INCI, so the upper end is driven by sensorial/stability constraints (odor/color, viscosity, electrolytes) and supplier-recommended use levels rather than a hard regulatory cap.