A fresh, cooling scent in body washes, lotions and balms. It adds fragrance and a tingle, not a skin benefit, and is toxic if swallowed.
Eucalyptus oil is mostly 1,8-cineole (eucalyptol), which gives the familiar medicinal, cooling smell. In body care it is a fragrance ingredient, often paired with mint for a tingling feel. Any 'clearing' sensation from a eucalyptus body wash comes from the scent.
No trials show eucalyptus oil in personal-care products benefits skin. Its effects are sensory: scent and a mild cooling feeling.