[Mark McM]

Originally Posted by bicycletricycle

Not all prescribed substances are banned. It is not the criteria being used, I am actually unclear what the criteria is. Lots of substances are dangerous if abused used incorrectly. Some are banned and some aren’t.

I mentioned the prescription aspect to point out the drugs you mention have already been determined to be potentially dangerous (and thus require a prescription).

As far the criteria for what substances are banned - From the WADA Prohibited Substances web page:

Typically, a substance or method will be considered for the WADA Prohibited List if the substance or method meets any two of the following three criteria:

It has the potential to enhance or enhances sport performance
It represents an actual or potential health risk to the athlete
It violates the spirit of sport

Originally Posted by bicycletricycle

Besides, if danger is the worry than let them take it under doctors supervision.

That would violate medical ethics. Some substances can cause potential danger to health, and so they aren't to be prescribed unless there is a medical necessity - in other words, in cases where the danger using the substances outweighs the danger of not using it. Administering potentially dangerous substances to healthy individuals who don't need it violates the oath of medicine.