Preservation in sunscreens - Microbiology point of view

Difficulty in preservation of sunscreens

Difficulty in preservation of sunscreens is a known fact. Different UV-filters have an induced effect on bacteria growth and can even exacerbate contamination of the sunscreen formulation.

Use of broad-spectrum UV-filters

Use of broad-spectrum UV-filters for greater protection can help in minimizing solar UV-induced skin changes. Nevertheless, the same UV-filters can challenge the preservation process of sunscreens.

Derivatives of some UV-filters can be part of metabolic pathways in different microorganisms and can even activate them. Metabolic pathways in microorganisms are responsible for synthesizing and breakdown of molecules by utilization and energy release during the process. 

Metabolic pathway of each microorganism

As part of the metabolic pathway, microorganisms secrete different compounds, such as  siderophores, which are used for their survival. 

There are UV-filters which can enhance the production of siderophores. These compounds can be a growth promoter for different microorganisms.

Understanding the metabolic pathway of each microorganism, is one of the scientific keys in solving the preservation challenge.


Regina Shulkin – Microbiology scientist, Sharon Laboratories
Inbal Israeli – Cosmetic applications manager, Sharon Laboratories


To learn more about SharoSUN™ focused preservative solution for sunscreen formulations  >> click here 

To learn more about the challenges in formulation of sunscreen products  >> click here



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