It seems like every other day that you come across a story about a mass overdose, with dozens or hundreds of people hospitalized after a new batch of dangerous drugs hits the street. The opioid epidemic has put drug abuse in the national spotlight, but it's not all hype: Illicit drugs are increasingly unsafe today.

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Opioids such as heroin and prescription painkillers killed more than 28,000 Americans in 2014, according to the Centers for Disease Control and Prevention. Now, newer, more potent opioids such as fentanyl — which is at least 50 times stronger than morphine — are on the rise. Law enforcement found that drugs testing positive for fentanyl quadrupled from 2013 to 2014.

And there's a disturbing trend behind the recent spike in mass overdoses in America. Potent opioids are being combined with other drugs to make them more potent, and that's not always being disclosed to the buyer. Heroin laced with an elephant tranquilizer called carfentanil recently killed eight people and hospitalized 35 others in a three-day time span in Ohio, for example.

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That's an extreme example. More commonly, drug concoctions that are designed to resemble prescription drugs such as Oxycontin and Xanax are being pressed with other substances, including fentanyl, and those combinations can be fatal.

"Anyone can press a pill these days," Lori Kufner, who works at the harm reduction organization Trip! Project, told Vice. "It's not very expensive or difficult. ... Even if you look it up, and it matches something you saw online, it could still literally be anything."

Drug purity has always been a concern, but it used to be that buyers fretted over being ripped off: that their dealer would sell ecstasy that consisted of more caffeine than MDMA, for instance. Now it appears that the opposite concern is growing, with harm-reduction advocates encouraging users to buy at-home testing kits — and naloxone kits in the event of an overdose.

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It's unclear when drugs (particularly opioids) became less safe and pure, but it stands to reason that the cause behind the shift is directly linked to the opioid epidemic. The number of Americans who abuse heroin and prescription painkillers has steadily risen throughout the 21st century, according to the National Institutes on Drug Abuse. And as the market for illicit drugs has increased, opportunistic sellers save money by making doses more potent, because the genuine pure pills are expensive and increasingly regulated.

The market demands prescription painkillers and anti-anxiety medication such as Xanax. But when a dealer can't get his hands on the actual branded pills, they have the financial interest and resources to create their own versions.

Still, even some drug experts are baffled by the trend, The Guardian reported. After all, "[killing] off your entire customer base is not economically viable," said one public relations official from the dark web, which sells illegal drugs on an encrypted online marketplace.

[h/t Vice]

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