Yes, Tylenol is a scary one that was not well publicized for a long time. We basically stopped giving it to Mom because she was so small and we couldn't be sure what dosage would be too much. We gave liquid Advil (ibuprofen) and watched her like a hawk.
The thing about substances that promote quicker healing is that they might do so by encouraging cells to divide more efficiently, and cancer is based on rapid cell division. So can some of those substances trigger rogue cell division? When will we know--before people start taking it, or after? That's a huge risk to take, even for fame and money.
Speaking of money, a friend of mine pointed out that in the days when his father was a football player (for the Eagles, over forty years ago), he got a salary. A good salary compared to office workers, but a salary within the normal range of achievement. These days the money is off the scale for many athletes, especially if you add deals with sponsors. So the incentive to give oneself an edge is overwhelming. (Not so much with skating these days, of course!) I mean, wouldn't many people be willing to risk legal or medical complications to be the face of Nike or Adidas?