Interactions with Malassezia yeasts

Malassezia are natural members of our skin's microbiome. They are lipid-dependent organisms and prefer fatty acids with carbon chain lengths between 11 and 24 carbon atoms. Sebum, the skins natural oil, is the yeast's primary source for fatty acids in this range.

Products containing C11-24 acids can provide excess nutrients for the yeasts to exploit, promoting their growth and colonization on the skin. As a result, most individuals are highly likely to experience a reaction from formulations that contain these ingredients.

Rating: Highly reactive for most individuals

Many factors can contribute to the severity of a reaction to one of the C11-24 acids. The chemical composition of an acid varies depending on its source, which alters the availability of nutrients for Malassezia yeasts. In addition, the acid's concentration within a product or the presence of other ingredients can affect its influence.

Despite these factors, the C11-24 acids remain a direct source of nutrients for Malassezia yeasts. As their presence significantly elevates the risk of an adverse skin response, we strongly recommend avoiding products containing these ingredients.

Matching requirements

Sezia checks for the names of the C11-24 acids, in common or IUPAC form. It also checks for acid groups that include them.