Colloidal silver

Colloidal silver has excellent antibacterial effects, acts against redness and inflammation, cleanses and regenerates the skin, and regulates sebum production. It prevents the spread of viruses, bacteria, and microorganisms. It is a stable suspension of silver nanoparticles in water, obtained by electrolysis, used in cosmetics as a broad-spectrum antimicrobial agent. These particles bind to the sulfhydryl groups of proteins and enzymes in bacterial cells, disrupting their membranes and increasing the production of reactive oxygen species (ROS), which leads to the death of pathogens without significantly affecting the skin barrier at low concentrations. In cosmetic formulations, it also serves as a preservative instead of parabens, preventing the growth of bacteria such as E. coli, Pseudomonas, and S. aureus.

Its main function is strong antibacterial and antimicrobial action, which reduces the number of harmful microorganisms on the skin. It soothes irritation and redness, supports skin regeneration by minimizing inflammation and promoting wound healing. It regulates sebum production by inhibiting the growth of acne-associated bacteria, thereby contributing to a more balanced complexion. It also has mild antioxidant properties through the increase of ROS in bacteria, which protects the skin from oxidative stress. At concentrations of 4-8 mg/L (ppm), it shows a bactericidal effect against Gram-negative bacteria such as A. baumannii, P. aeruginosa, and E. coli after just 8 hours, reducing bacterial counts by more than 3 log10 CFU/mL. At 1-2x MIC, it is bactericidal within 24 hours against multiple pathogens.

It is especially recommended for oily, acne-prone, problematic, and sensitive skin, where it helps reduce inflammation, acne, and irritation. It is also suitable for dehydrated or irritated skin thanks to soothing and barrier-supporting effects in combination with oils or herbal extracts. For mature skin, it may support healing and protection against infections. The maximum concentration in cosmetics is 1% according to EU regulations. It is not recommended for long-term internal use because of the risk of argyria, but topically it is safe and non-irritating.

A study published in the International Journal of Molecular Sciences (2020) demonstrated that colloidal silver at MIC90 concentrations of 4-8 mg/L is bactericidal against 270 isolates including MDR strains of A. baumannii, P. aeruginosa, E. coli, S. aureus, and Enterococcus spp., reduces bacterial counts by >3 log10 CFU/mL after 8-24 hours, and significantly increases ROS production in Gram-negative bacteria. Another study, however, found no antimicrobial effect at 22 ppm in agar tests against the tested pathogens.