When a medication is being evaluated to modify the behavior of a person with autism, one must assess the risks versus the benefits. The benefits of the medication must outweigh the risks.
Some medications can damage the nervous system and other internal organs, such as the liver.
These risks are greatest in young children because an immature nervous system may be more sensitive to harmful side effects. A good general principle is that the use of powerful drugs should be avoided in young children when the risk is great. The younger the child the greater the risk. For example, it would be justified to give a young child Prozac to stop severe self-injury, but it would probably not be justified if the only effect was that it made him slightly calmer. If a medication improved language, its use would probably be recommended.