What is it?
An ingredient made by growing yeast (Saccharomyces) in the presence of copper ions and then extracting the fermented product, as defined in the EU ingredient database, which lists it as a skin-conditioning agent. It is used in hair and skin care. The EU database also lists a filtered lysate version of this copper ferment and similar yeast ferments made with zinc, iron, magnesium and other minerals.
Key information
- The EU defines Saccharomyces/Copper Ferment as an extract of yeast fermented in the presence of copper ions, used as a skin-conditioning agent.
- In 2024 the CIR Expert Panel concluded that Saccharomyces Ferment and related yeast ingredients are safe as used; the copper version was not part of that review.
- Yeast ingredients for cosmetics are heat-inactivated, so no live yeast remains in the finished ingredient.
- In 2025 the CIR found copper gluconate safe in cosmetics, noting that copper is an essential nutrient and that clear-cut copper allergy is extremely rare.
More information
According to a manufacturer quoted by the Cosmetic Ingredient Review (CIR), yeast ingredients are heat-inactivated at 80 degrees Celsius, broken open and filtered; because yeasts are viable only below 50 degrees Celsius, no live yeast remains in the finished ingredient. In this version, copper ions are present during fermentation; the label does not say how much copper the finished ingredient contains.
In 2024 the CIR Expert Panel reviewed 56 yeast-derived ingredients and concluded that Saccharomyces Ferment, Saccharomyces Ferment Filtrate and related generic yeast ingredients are safe in cosmetics as used, when made from yeast species with food-use status and skin sensitization data, such as baker’s yeast, Saccharomyces cerevisiae. The Panel noted that allergic reactions to yeast have been seen mainly in people breathing in high concentrations of live yeast, while yeasts in cosmetic ingredients are lysed and inactivated. Saccharomyces/Copper Ferment itself was not among the ingredients reviewed, and we found no published safety studies of it.
On the copper side, the CIR concluded in 2025 that copper gluconate is safe in cosmetics as used. It noted that copper is an essential nutrient, that copper gluconate did not irritate or sensitize skin in several human patch tests, and that, given how widely people touch copper in coins, jewelry and other objects, clear-cut cases of copper allergy are extremely rare. In rinse-off products such as conditioners, contact with skin is brief.
Sources: European Commission CosIng: Saccharomyces/Copper Ferment; CIR: Safety Assessment of Yeast-Derived Ingredients as Used in Cosmetics (final report, 2024); CIR: Safety Assessment of Copper Gluconate as Used in Cosmetics (final report, 2025)
