Experts say this possible side effect is rare but parents need to be made aware of this.
The study in the journal Pediatrics found ADHD drugs can cause psychosis and mania in some patients, including some with no obvious risk factor.
In some cases, children hallucinated that worms, bugs or snakes were crawling on them.
The FDA is urging doctors to discuss the potential side effects with parents and children to help ease their anxiety if such symptoms should occur.
