A new direction in the development of pharmaceutical and cosmetic products, provides for the widespread use of pigment containing components of extracts of microalgae and blue-green algae. However, the use of these components requires a deeper study of their effect on humans, including on their microbiota. In our experiments, it was found that the extract of the blue-green algae Arthrospira platensis (commercial name of the drug Spirulina), with a phycocyanin content of 38%, is able to influence the overall microbiota of human skin, and to varying degrees of effectiveness depending on the concentration of the drug. It is shown that the effect of the studied extract has a dose-dependent effect, both when affecting the general microbiota of human skin and on representatives of its gram-positive microbiota. The gram-negative microbiota of human skin is less sensitive to the action of the extract of the blue-green algae Arthrospira platensis (commercial name of the drug Spirulina), since only at a concentration of 200 mcg/ml there was a significant low increase in biomass.