But now school children are taking them too, said UK Sport - a sports agency which is funded by the government.
Staff at UK Sport have had lots of calls from worried parents, who said they've found their children with steroids, or that their child wants to take them.
The reasons children give for taking them are:
- To stop bullies
- To get a better body
- To get onto a school team
Only about one per cent of boys aged between 11 and 15 years old admitted to taking steroids in a government survey, but there are fears that that's on the rise.
For more details or help dealing with bullies, click on the ChildLine website to the right of this page.