When Dr. Eriko Onishi came to the United States from her home country of Japan, she ended up with culture shock on the number of opioids being prescribed.

Onishi got her medical training in Japan and spent about a year there practicing medicine before coming to the United States. She was used to that country’s strict attitudes around opioid painkillers like Vicodin or Oxycontin, which are generally only prescribed in cases where a patient is in severe pain, as with cancer. In Japan, opioids for acute pain aren’t typically covered by insurance.

When Onishi started practicing family medicine in Oregon, she was shocked to see patients getting opioids for injuries as minor as toothaches and sprained ankles. And she started seeing a disturbing trend among her own patients: people constantly requesting opioids for pain.

“It’s the patient begging you to ‘give me the opioid,’” Onishi said.

Onishi started wondering about a question at the heart of the American opioid crisis: Why is the United States such an outlier when it comes to dependence on powerful, addictive painkillers? After all, people in other countries also break bones, have surgery, and suffer from back pain and arthritis.

But the United States stands out for the sheer amount of opioids like Vicodin and Oxycontin it consumes, fueling a deadly drug epidemic. With just 4 percent of the world’s population, the US accounts for about 27 percent of the world’s drug overdose deaths.

The federal government estimated 8.5 million Americans, about 3 percent of the population, misused opioid painkillers in 2015, and 2.5 million were addicted to either painkillers or heroin. More than 33,000 people died that year from overdoses.

The European Union’s entire population exceeds that of the United States, but it has a fraction of the opioid use. Out of the approximately 507 million people living in the EU in 2014, 1.3 million — or 0.4 percent — were considered high-risk opioid users. That same year, officials recorded 6,800 drug overdose deaths in the EU; opioids were to blame in about 80 percent of those deaths.

There are no corresponding statistics for Japan, but if you compare the United States to the entire continent of Asia, you see a similar picture. In 2015, 52,400 Americans died from drug overdoses, while about 62,000 people in Asia did.

Part of the difference is cultural: American and Japanese doctors view pain differently. Part of it is regulatory: In Europe, opioids are much more tightly regulated. The American opioid epidemic is what you get when you pair a culture that values treating pain at all costs with a regulatory environment that makes dangerous and addictive drugs relatively easy to obtain.

Opioid use in the US blows other countries away

When you compare United Nations data on the top 25 countries that consume the most opioids, the United States is far and away at the top of the list. The standard daily dose per million people in the United States is 50,000 doses of opioids. That’s every day.

International data shows that despite making up 4.4 percent of the global population, the US gobbles up a disproportionate amount of the world’s opioid supply; about 30 percent of the total. And Americans use almost all of the entire world supply of certain opioids, including a full 99 percent of the world’s hydrocodone supply.

Drug consumption in the United States can’t be easily blamed on something simple, like an aging population with more pain. In fact, some European countries and Japan have older populations than the United States and still use fewer opioids than we do.

Instead, the answer has to do much more of a focus in the United States on perfecting someone’s life, and a lot less willingness on the part of both patients and doctors to accept the existence of pain.

“A bit of this is cultural expectations about how fixable is life,” said Stanford psychiatry professor and addiction researcher Keith Humphreys. “America is still young and thinks life can be perfected.”

Japan is skeptical of opioids for acute pain

In Oregon, Onishi studied doctors in the United States and Japan to find out more about why many American patients expected opioids to be prescribed even for smaller injuries. She found the American doctors who responded were far more likely to prescribe opioids than their Japanese counterparts.

About 50 percent of the 461 Japanese doctors Onishi surveyed said they prescribed opioids for patients with acute pain, versus a full 97 percent of the 198 American doctors who participated in her study.

Japanese doctors were slightly more willing to prescribe opioids for chronic pain, about 64 percent versus 91 percent of US doctors.

The US and Japan have vastly different cultural views when it comes to treating pain, especially acute pain after an injury, according to Onishi. Many people in the country also worry about the potential of getting addicted.

Japan was so reluctant to prescribe opioids that in 2007, rather than asking why Americans prescribe so many painkillers, the New York Times asked why Japanese doctors prescribed so few. The answers ranged from prevailing attitudes that pain was something to be endured to concerns about morphine — both its addictive properties and its traditional use to ease pain, especially in end-of-life care.

“People hate morphine because they think, ‘As soon as the doctor injected morphine, my father died,’” neurosurgeon Dr. Fumikazu Takeda told the New York Times in 2007.

Meanwhile, in the United States, doctors started making the case in the late 1990s that pain needed to be treated aggressively. This shift in attitude was fed by drug manufacturers like Purdue Pharma, which were trying to increase sales for extended-release narcotics like OxyContin. Prescription opioid sales nearly quadrupled from 1999 to 2014, even though Americans didn’t report a huge change in the amounts of pain they felt.

Doctors in Japan have started to come around to the idea of prescribing opioids for people with severe, chronic pain, such as cancer patients, but not for more everyday acute pains like broken bones.

Another barrier to getting opioids for acute pain: Japanese insurers simply won’t cover it. “Unless you need surgery, you don’t get opioids,” Onishi said. “The culture and the insurance make a big, big difference.”

Notably, Onishi’s survey also revealed doubts among American doctors about overprescribing. Out of the American doctors Onishi surveyed, 95 percent said they believed opioids were being relied on too often, whereas just 6 percent of Japanese respondents had the same reservations.

In her own practice, Onishi is trying to have open conversations about prescribing with her patients, pushing back when some request opioids and exploring alternative ways to treat their pain. She said she’s trying to open up a dialogue so that patients understand “we’re not the bad guys.”

Western Europe regulates opioids more tightly

In Europe, the way patients and doctors view pain isn’t that different from attitudes toward pain in North America, according to Canadian researcher Dr. Benedikt Fischer. But Europe still has much lower rates of opioid prescription. Germany, the country that consumes the most opioids in Europe, prescribes pills at about half the rate of the US.

A few years ago, Fischer and a team of researchers at the University of Toronto set to explain the difference between opioid prescribing in North America and Western Europe. They found that pharmaceutical regulation (or lack thereof) plays a large role in how opioids are advertised, sold and prescribed in the US and Europe.

“In North America, health is much more of an industry than in Europe,” Fischer said. “Europe is generally much more regulated. That’s not universally the case, but in regards to medicine and health care, that’s probably more often the case than not.”

Western Europe is actually starting to catch up to the United States for rates of opioid prescribing, Fischer said. (Europe’s opioid problem has largely been restricted to heroin, although there are signs of prescription painkillers and synthetic fentanyl becoming a problem.)

But the two are very different when it comes to how the government regulates opioids, controlling where and how pharmaceutical companies are able to advertise, and also the setting where doctors can prescribe opioids.

One of the biggest differences is how centralized this regulation is across Europe, including limitations on how much doctors can prescribe and cost coverage. Comparatively, regulation in the United States usually happens on a case-by-case basis, with individual states running prescription drug monitoring programs where individual doctors upload information.

In Europe, opioids are generally dispensed by specialists, not primary care doctors. As in Japan, they are more frequently used when patients are in severe pain from a disease like cancer. They are also prescribed mostly in hospital settings, rather than in community-based clinics. There is also a strict ban on pharmaceutical companies advertising directly to patients in Europe.

Contrast that to the United States, where primary doctors write half of the nationwide prescriptions for opioid pain relievers, according to the CDC.

At the root of these differences in prescribing practices are even bigger differences among health care systems. For instance, nearly all European countries have national health systems where doctors are salaried, and don’t get paid depending on how much medical care they give, or how many pharmaceutical drugs they prescribe.

There’s much more private competition and fee-for-service medicine in both the US and Canada.

Fischer compared opioid prescribing rates in Ontario, Canada to those in Germany, and found that in Germany, just 4.5 percent of the total population reported using prescription opioids. In just one Canadian province, 20 percent of the population reported using them. The rate is higher in the US, with about 38 percent of the population being prescribed opioids.

As the American health care system has grown, it’s gradually pushed out smaller private practices in favor of large health care systems that are part of larger health networks and hospitals.

That all feeds into what addiction specialist Dr. Anna Lembke has named the “Toyotazation of medicine,” because it’s like an assembly line: When you go into the doctor’s office for an appointment, your doctor is rushed and only able to spend a few minutes with you before rushing off to see another patient.

“Nobody pays us for talking to people, we don’t value that,” Lembke said.

Pain is complex and multi-faceted, and it can be cause by different things, including an injury, chronic pain due to nerve damage, or maybe even psychological pain from a traumatic event.

If doctors had more time, they could spend time talking to patients, getting to the root of the problem, and refer patients to physical therapy for back pain that won’t go away, or to a mental health therapist to work through anxiety and post-traumatic stress disorder. But often, there’s not enough time for those in-depth conversations to take place in a primary care office.

“In the absence of time having hard conversations, you just prescribe an opioid,” Lembke said.