"I'm not prone to dramatic statements," Robert Anderson, chief of the mortality statistics branch at the National Center for Health Statistics, told NPR. "But I think we should be really alarmed. The drug overdose problem is a public health problem and it needs to be addressed. We need to get a handle on it."

The last time the U.S. life expectancy dropped was in 1993 because of the AIDS epidemic. The rate hasn't fallen for two consecutive years in the U.S. since the 1960s, NPR reported.

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According to the CDC, much of the increase in fatal opioid overdoses was driven by the rise in illegal synthetic opioids other than methadone, such as fentanyl and tramadol. The rate of overdose deaths involving these synthetic opioids doubled between 2015 and 2016, from 3.1 per 100,000 in 2015 to 6.2 per 100,000.

Each year since 2013, the rate of deadly overdoses from synthetic opioids other than methadone have increased by an average of 88 percent. Heroin, an illegal opioid, claimed more than 15,000 lives in 2016, compared to nearly 13,000 in 2015.

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By comparison, opioids killed more people in 2016 than car crashes (about 37,400), guns (about 38,000) or breast cancer (about 40,000).

Age-adjusted drug overdose death rates, by state: United States, 2016

Twenty-two states, plus Washington, D.C., had overdose death rates higher than the average of 19.8 fatalities per 100,000 people.

West Virginia, Ohio, New Hampshire and Pennsylvania were among the worst.

Drug mortality has increased among all age groups since 1999, but it's currently highest among those ages 25 to 54.

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"It's even worse than it looks," Keith Humphreys, an addiction specialist at Stanford University, told the Washington Post. Research has shown that the actual number of opioid deaths could be 20 percent or more than the figures reported.

“We could easily be at 50,000 opioid deaths last year,” Humphreys said. “This means that even if you ignored deaths from all other drugs, the opioid epidemic alone is deadlier than the AIDS epidemic at its peak.”

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Q: What is an opioid?

A: According to the National Institute on Drug Abuse, opioids are a class of drugs that bind to opioid receptors on cells in the brain and throughout the body, cells that may control your digestion, pain and other functions.

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Your body already contains some opioid chemicals (like endorphins), which help relieve pain and give you that positive feeling after exercise. But when opioid drugs attach to the cell receptors in the brain, they can dull your perception of pain even more, which is why some opioid drugs are prescribed by physicians for patients with severe injuries.

Misuse of opioids starts when prescription opioid drugs or illegal opioids (like heroin) are used to feel euphoric. The misuse of opioids can lead to addiction and can be potentially fatal.

» RELATED: US gun death rate up for second straight year, drug deaths rising faster than ever

More from the CDC.