Silver

Topical silver (most often as metallic silver or silver salts in antimicrobial/wound and acne products, typically at low concentrations) is generally well-tolerated, but it is not inert because silver ions can be cytotoxic to keratinocytes at sufficient exposure and can irritate compromised skin. Clinical experience and patch-test literature suggest irritation is uncommon but possible, and allergic contact dermatitis has been reported to certain silver compounds (more than to elemental silver). Given sensitive/eczema-prone populations and leave-on use, I rate it as gentle with a small but real irritation/sensitization risk. Safety Notes: In consumer cosmetics, silver is most often present at trace antimicrobial/odor-control levels (e.g., colloidal/nano silver or silver salts in deodorants, lotions, masks, and cleansers), with real-world INCI usage commonly in the ~0.0001–0.05% range. The upper end is represented by high-strength OTC topical antimicrobial/barrier products marketed with “silver” (e.g., silver gels/creams using colloidal silver or silver-containing complexes), which can reach about 0.1–0.5% silver in leave-on formats; rinse-off products typically sit toward the lower end due to cost and deposition limits. Concentrations above this are uncommon for general-consumer cosmetics and more associated with medical devices or professional/prescription antimicrobial treatments rather than standard OTC skincare.