Cocaine has been used recreationally for hundreds of years, and medicinally for just as long. It was even a founding ingredient of Coca-Cola. While you can’t get it in soft-drinks anymore, it is still used clinically in a few different ways.
Cocaine is primarily used as a topical anesthetic as well as a vaso-constictor, so it can numb an area before a procedure and decrease bleeding and swelling after. In certain cases, cocaine eye-drops are used to check for a problem with the sympathetic nervous system (i.e. fight-or-flight). Because cocaine directly activates the sympathetic nervous system, if the eye-drops don’t cause pupil dilation, then there might be a problem somewhere in that pathway (called Horner syndrome). WebMD says that common cocaine side-effects include an unusual sense of well-being. Not surprisingly, in its purified form, cocaine is one of the most addictive substances around.