OxyContin abuse has long been recognized as one of the widest painkiller addiction in the United States. Since 2010, OxyContin abuse dropped from 36 percent to 13 percent, after the producer redesigned it. Whereas stopping OxyContin abuse seems to work, more and more users switch to heroin.

A letter published this Wednesday in the New England Journal of Medicine gives the other side of stopping OxyContin abuse. In the early 2000s, the United States was witnessing a dangerous trend. OxyContin abuse was on the rise, as patients would misuse prescriptions to get high. The pills would be crushed or dissolved becoming easier for addicts to take in.

In 2010, Purdue Pharma, OxyContin’s maker, decided to reformulate the painkiller to make it harder for addicts to use it for a high. Two years later, a new study finds the decision had actually delivered results. OxyContin abuse was cut to half during this time, but people looking for a high turned to other potent opioids, such as heroin.

Theodore Cicero, psychiatry professor with St. Louis’s Washington University and co-author of the study, potent opioids such as oxymorphone, hydromorphone, fentanyl and even heroin have replaced OxyContin. However, as the co-author points out, the most unexpected turn of events, is users’ decision to switch to heroin.

“A number also switched to heroin, which I think was the most unexpected finding” reads Cicero’s explanation. According to the study, as of this March there 20 percent of those that once abused OxyContin, have selected heroin as their drug of choice. Three years ago, that percentage was half of what it is today.

“There is a percentage of the population that is going to, that wants to, use and abuse drugs. The treatment of the problem can’t just be focused on the drugs they’re taking” professor Theodore Cicero explained. “If there’s a demand there, it will be met” he added.

Wilson Compton, director of prevention research with the National Institute on Drug Abuse, worries heroin consumption will spike: “We are seeing some possible evidence that heroin may be increasing in prevalence in some areas around the country”.  Compton also added “Unfortunately what we’re seeing in this report is that you can push down on one area, but may pop up in another area”.