Algae

In cosmetics, “algae” typically refers to algae-derived extracts (polysaccharides, proteins, minerals) used at low concentrations for soothing, film-forming, or hydration; these are generally well-tolerated and not intrinsically irritating. However, botanical extracts have inherent variability and can contain trace proteins/iodine or processing impurities that occasionally trigger stinging or dermatitis in highly reactive or eczema-prone patients, especially on compromised skin. Given this low-but-real sensitization/irritation potential, it fits best as a gentle ingredient rather than inert. Safety Notes: In commercial skincare, algae-derived materials are often used as extracts/ferments in leave-on serums, toners, and creams at very low levels (down to ~0.0001–0.01% as supplied extract/active within blends) primarily for marketing/antioxidant/soothing claims. Higher levels are seen when the algae ingredient is a primary functional component (e.g., seaweed/algal gels, thalassotherapy masks, body wraps, hydrogel-style masks, and emulsions built around algal biomass or concentrated extract powders), where total algae-derived solids can reach ~5–20% in consumer-available products. Rinse-off products typically sit mid-range (e.g., cleansers/masks around ~0.1–10%) because higher loads can impact viscosity, color/odor, and stability, but specialty masks and wraps can push to the top of the range.