Some medications used to treat ADHD are prescribed off-label, outside the scope of their FDA-approved indications for various reasons. The U.S. FDA requires two clinical trials to prove a potential drug's safety and efficacy in treating ADHD. The drugs below have not been through these tests, so the efficacy is unproven (however these drugs have been licensed for other indications, so have been proven to be safe in those populations) and proper dosage and usage instructions are not as well characterized.