An anesthetic (numbing) agent added to some numbing sprays to desensitize tissue and to relieve discomfort. Unlike other numbing ingredients such as benzocaine and lidocaine, lauromacrogol is fairly mild; it is also used in some balms and ointments as an anti-itching agent. Synonyms for lauromacrogol include polidocanol, laureth 9, and PEG-9 lauryl alcohol.

While this ingredient is fairly gentle and well tolerated, it can cause a warming feeling that some users find uncomfortable. It can also cause a potentially serious allergic reaction when applied in large amounts (this is rare for topical preparations). Side effects can include hives, pain, or burning.