If your doctor prescribes a particular medicine, the thinking goes, how can it possibly be harmful? If it was, the physician wouldn't prescribe it. Many very helpful medications commonly prescribed by doctors are safe to take — if you take them as prescribed, which means in the exact dosage and for the exact (normally short) time frame specified by your physician. If taken in higher dosages or for a longer time, however, these same medications can quickly turn addictive and even lethal because they affect the same parts of the brain as street drugs [sources: Carise, Sack].
Controlled prescription drug abuse is actually America's fastest-growing drug problem according to a 2013 study by the U.S. Department of Justice's Drug Enforcement Agency. Some of the drugs most commonly abused include Xanax, Valium, Ambien, Tylenol with codeine, OxyContin and Percocet [source: National Institute on Drug Abuse]. Unfortunately, too many people still believe these prescription meds are not dangerous or addictive as street drugs. But that is just plain false.