A drug often given to addicts on their deathbed has enabled a woman who has never felt pain to experience it for the very first time — and some are wondering what the health ramifications for this discovery are.

The woman was given the drug naloxone and then burned with a laser, an experiment she “enjoyed,” said researcher John Wood of the University College London according to a Yahoo News report.

It’s a rare genetic condition where nerve cells are unable to send pain signals to the brain, and it’s not as nice as you think it is. As it turns out, pain has a very useful purpose in the body, and those born without these pain signals often chew off their own fingers and lips without realizing they’re doing damage to their body.

But this woman’s condition could pave the way to new pain treatments for those with chronic problems with it, although scientists know they will have to be careful. Opiods and Nav1.7 blockers should not be taken through one’s lifetime, doctors say.

Wood and his colleagues were intrigued by this woman’s case and examined mice that had been genetically modified to lack Nav1.7, so they wouldn’t feel pain either. They found that the nerves in these mice had a large increase in the expression of genes responsible for opioid peptides, which is the body’s naturally produced painkiller. Because the mice were producing more of these, it could explain why they don’t feel pain when lacking Nav1.7.

Naloxone, sometimes called Narcan, is a medication meant to reverse the effects of opioids, especially in cases where patients have overdosed on the drug. It is often injected into a muscle and works within five minutes, and the effects last about a half hour to an hour. Sometimes multiple doses are required. It was first patented in 1961 and was approved for treating opioid overdose in 1971.