What are commonly misused prescription drugs? What drug has killed the most people? What are the most dangerous drugs? Whether you’re taking Ambien to help you sleep, Adderall for ADHD, or a pill for anxiety like Valium or Xanax, you have to be careful: many of these prescription pills can be deadly if they’re misused. Check out WatchMojo’s list of the Top 10 Abused Prescription Drugs to see which are commonly misused prescription drugs and to learn the common side effects of the drugs.