No harm. Hydroxyethyl cellulose is harmless to hair, because hydroxyethyl cellulose is a white or yellowish, tasteless and nontoxic fibrous or powdery solid, which is etherified by basic cellulose and ethylene oxide (or chloroethanol) and belongs to nonionic soluble cellulose ethers. It has good characteristics of thickening, suspension, dispersion, emulsification, adhesion, film formation, moistureproof and providing protective colloid, and is widely used in petroleum exploitation, coating, construction, medicine and food, textile, paper making and polymer polymerization. In shampoo, hydroxyethyl cellulose is usually used as thickener and stabilizer, which helps to improve the overall quality and experience of shampoo, so it is harmless to hair.