I’m not sure I’ve ever met an opioid user who didn’t want to quit, and as an emergency room doctor, I’ve met a fair number of users. But the chemical need of the addiction can be indomitable. And the nature of that dependence is often misunderstood. It’s not only the high that keeps most users hooked—it’s also avoidance of the special hell of withdrawal.

This is why, when a heroin user who had just overdosed in his mother’s bathroom was brought to the ER where I work, he immediately shot up again in the hospital bathroom. Paramedics had given him naloxone, the antidote for opioid overdose. It saved his life, but the medication creates instant withdrawal. His brush with death had fazed him less than his roiling dope sickness.

It’s also why a man who had just been placed on a ventilator for a major overdose yanked out his breathing tube in the ICU, eloped from the hospital, and used again in the parking lot. One of my colleagues, heading home from the hospital, found him lifeless on the pavement and administered naloxone. We placed the man back on a ventilator and returned him to the ICU, where he woke up, yanked the tube, and escaped again in search of a fix.

With proper treatment, withdrawing from opioids won’t kill you, but it can make you want to die. The body comes to depend on the presence of opioids to maintain a sort of artificial homeostasis. “Morphine becomes a biological need just as water,” William Burroughs wrote in 1956. When the counterweight of an opioid is removed, the body responds with mayhem—diarrhea, vomiting, cramps, shivering, palpitations, anxiety, agitation, paranoia, and, weirdly, interminable yawning and sneezing. Burroughs called it a “nightmare interlude of cellular panic.”

Prescription medications like methadone and Suboxone, themselves opioids, are highly effective in blocking withdrawal, preventing overdose, and helping opioid users rebuild their lives. But some feel that these medications trade one form of dependence for another. And tapering off of methadone or Suboxone can trigger the same symptoms of withdrawal as heroin or oxycodone. We don’t have anything like a cure for opioid addiction.

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The desperation of some users to get clean leads them to seek hope underground. A while ago, I began to hear about a rogue treatment called ibogaine. It’s illegal in the US but draws users south to Mexico, where a network of unregulated clinics has emerged to offer it. Extracted from the root of a plant native to West Africa, the drug produces psychedelic effects akin to a waking dream and is said by its advocates to spirit away withdrawal symptoms with a single dose, leaving users sober and uninterested in smack. But there’s a catch—apparently, the treatment could kill you.

A drug that provides rapid detoxification from opioids in a single dose struck me as hugely promising. It could change everything, unless the risks were real.

I wanted to see for myself how it was being used.