Doctors often use opioid prescription painkillers to treat moderate-to-severe pain, typically after a surgery, injury or the diagnoses of serious health conditions such as cancer, according to the CDC. More recently, prescribers have become more accepting of using such drugs to treat non-chronic pain outside of cancer, such as osteoarthritis. Some of the most common, Schedule II (below heroin in severity) prescription opioids involved in overdose deaths include:

Hydrocodone

A short-acting, semi-synthetic opioid, sold as Vicodin or in extended-release form as Zohydro and Hysingla. Sales of the drug increased 280 percent between 1997 and 2007.

Methadone

Possessed analgesic properties, but must be used with caution. It has a long half-life and can accumulate in the body, leading to overdoses, and can interact with various other medications. Sold as Dolophine and Methadose, sales increased 1,293 percent for the decade ending in 2007.

Oxycodone

A semisynthetic opioid with the same properties as morphine for its habituation, tolerance, physical dependence and withdrawal syndrome. Brands include OxyContin, Roxicodone and Oxecta. Sales increased 866 percent the decade ending in 2007.

Oxymorphone

Similar to oxycodone, it's a semisynthetic, powerful painkiller that has the same properties as morphine and tends to be habit-forming and bring about withdrawal symptoms. Sold as Opana.

*Sources: CDC, 2016; American Chronic Pain Association, 2016; and the American Society of Interventional Pain Physicians, 2012