Recreational is used to imply that things are taken through choice, rather than necessity, often as part of a social setting. Think Ecstasy at clubs etc. These are usually the type of things that produce a euphoric high, rather than having any noticeable physical effect like a true painkiller, or anti-inflammatory does.
I saw a FA poster about drug testing yesterday and two of the medications I take on prescription (including one for asthma) would see me fail their doping tests! The asthma inhaler is listed as a banned performance enhancing drug (true it does enhance my performance - it allows me to breathe), while the other is banned because it is a diuretic and has been used to disguise the presence of nandrolone!