Almost 60% of patients taking prescription opiate painkillers are prescribed potentially dangerous drug combinations, according to a study released on Tuesday by a prescription drug management company.

“There could be instances when prescribing these combinations of drugs is appropriate, but not at this scale,” said Lynne Nowak, a doctor with Express Scripts, a St Louis, Missouri-based company that processes more than 1bn prescriptions each year. “The fact that the majority of these patients are being treated by multiple physicians and pharmacies signals a communication breakdown that leads to dangerous use.”

The study, a Nation in Pain, was conducted using the anonymized records of more than 6.8 million Americans who had filled prescriptions for opioids between 2009 and 2013. Opioids, such as Vicodin and OxyContin, came to national attention as potentially dangerous in the mid-2000s when cities across the US started experiencing unusually high incidences of opiate overdose and addiction-related crime.

Express Scripts’ study found that while fewer Americans are prescribed opioid painkillers, those that are have more prescriptions and for longer. Both the number of prescriptions and the amount of medication distributed rose by 8.4%. While the number of long-term users remained relatively constant, the number of short-term users declined by 11.1%. Almost half of those who took the medication for 30 days remained on the drugs three years later.

The greatest growth in prescription use came in the 20-44 age group.

“The elderly have the highest prevalence of opioid use, but younger adults (age 20-44) filled more opioid prescriptions and had the greatest increase in the number of days of medication prescribed, per prescription, of any age group over the five-year period.”

More than half of users, almost 60%, were also prescribed potentially dangerous drug combinations such as benzodiazepines, a category of drugs used to treat anxiety. Together, opioids and benzodiazepines are the most common cause of overdose deaths involving multiple drugs, the report says. Other drug combinations, such as a combination of muscle relaxers, painkillers and anti-anxiety medications, called “Houston cocktails”, were used by 8% of those studied.

The fear of addicting patients to opiate-based medications was once so profound in the medical community that opium-derived drugs were rarely prescribed, even in extreme cases.

That changed in the 1990s during the pain management movement. In 1995, the Food and Drug Administration approved the use of OxyContin, meant to be a slow-release blend of oxycodone and acetaminophen (the active ingredient in Tylenol). At the time, expert panels recommended doctors prescribe the medication more often, citing a wide range of benefits despite slim research into the drug’s long-term effects.

But in what is now a well-documented form of abuse, those looking to use the painkillers recreationally only needed to crush the tablets and snort them for a euphoric rush. The movement and subsequent abuse is extensively chronicled in books such as Pain Killer and A World of Hurt.

From the time OxyContin was approved, it took another 15 years for the small Connecticut pharmaceutical company that created the drug to make it tamper-resistant (in other words, more difficult to crush and snort). By then, the Centers for Disease Control and Prevention was well on its way to declaring prescription painkiller abuse an “epidemic”.

The study’s results are also geographic. The use and abuse of these prescriptions painkillers is primarily concentrated in cities in four states – Alabama, Arkansas, Georgia and Kentucky, the study found.

“Government- and insurer-run drug monitoring programs can help prevent these possibly life-threatening scenarios, but unfortunately they are underused and vary by state,” Nowak said in a statement. “As more people gain access to health coverage, this problem will worsen if the country doesn’t use every tool at its disposal to ensure the safe use of these medications.”