Sunscreen was an ointment used for many centuries by Humans to protect themselves from sunburns.
In 2374,prior to the O'Brien family trip to Golana, Miles O'Brien inquired about the location of the sunscreen, only to be informed by his wife that she had already packed it. (DS9: "Time's Orphan")
Odo reminde Julian Bashir to take plenty of sunscreen on his trip to Casperia Prime. (DS9: "Inquisition")
Reginald Barclay wore sunscreen on his nose while on the beach in 2377. (VOY: "Inside Man")