As a manner of speaking, the word “banned” indicates a rule forbidding use in formal competition, under penalty of disqualification.
But, in the medical sense, there are a number of layers that restrict access to substances, even over the counter drugs are subject to regulation and laws, as well as prescription drugs, research chemicals, known toxins, and hazardous chemicals. All for many different reasons.
The class of anabolic steroids that body builders and weight lifters use are definitely going to land you in jail if you have them or provide them to a peer.
It doesn’t mean they are completely unavailable, but really, they are almost entirely outlawed to the same degree as crack, meth and so many other drugs around the world. Often veterinarians are the black or grey market source.
They cause harm, to the point of leaving behind a wake of debilitating destruction among the lives of users, causing awful damage that emerges later, in ruinously subtle ways, or suddenly killing without warning, by way of cardiac problems or strokes.
People use them, the results can be frightening and permanent, and a few years later, deadly.