When taken as prescribed, pain pills help people deal with severe injuries and chronic conditions. When taken recreationally, the same medications can become deadly.
Benzodiazepines and oxycodone are some of the most often-abused.
Among the most commonly prescribed depressants in the United States, "benzos" slow the body's nerve impulses. They are prescribed for anxiety, tension, panic, seizures and muscle cramps.
Brand names include Ativan, Klonopin, Valium and Xanax.
"Oxys" block pain receptors in the spinal cord. They also elevate levels of dopamine, the neurotransmitter linked with pleasure, and create a euphoric effect. When the brain is flooded with these narcotics, it stops making its own dopamine — so it starts craving the external infusion.
Oxys are derived from opiates, and are prescribed for injuries, arthritis, cancer and chronic pain.
Brand names include Roxicodone (rapid release) and OxyContin (time release). Combinations of oxys and other drugs include Percocet (with acetaminophen) and Percodan (with aspirin).
OxyContin, the most potent brand of oxycodone, was introduced in 1996 and quickly became "the most illegally abused drug in the last 20 years," according to the DEA.
Pills come in up to 80-milligram tablets and are meant to be swallowed whole. But abusers know that by chewing or crushing the pills they can bypass the time-release feature and instantly get the entire dose. They crush tablets then snort them, or dissolve them in water and inject them.
OxyContin had the most aggressive marketing campaign of any painkiller. Five years after it was introduced, sales topped $1 billion — more than Viagra. In 2007, the top three executives of Purdue Pharma, which produces OxyContin, pleaded guilty to criminal charges that they misled regulators, doctors and patients about the drug's risk of addiction and its potential for abuse.
Sources: Center for Substance Abuse Research, U.S. National Library of Medicine, The New York Times.