The name 'glycereth- is used to describe a PEG (polyethylene glycol) ester of glycerol. The number after the name "glycereth-" indicates the average number of molecular units (-CH2-CH2-O-), e.g. glycereth-7, glycereth-12, glycereth-20, etc. The consistency (liquid to solid) and chemical-physical properties of the glycereth-derivative depend on the respective number of molecular units.
Glycereth-20 serves as a humectant and viscosity regulator in cosmetics
The allergological relevance of the individual glycereth derivatives is not known.