Multnomah County sued nearly two dozen pharmaceutical drug makers Thursday, accusing them of fueling the opioid crisis by downplaying the risk of addiction and falsely claiming long-term use of pain pills was beneficial.

The county sued 23 national drug makers—including Perdue, Watson and Johnson & Johnson—as well as Oregon clinics and doctors who prescribed the drugs. The suit claims pharmaceutical companies launched a marketing scheme in the late 1990s to convince doctors and patients to use opioids for chronic pain, instead of sticking to their historically limited uses for short-term, acute pain and end-of-life care.

Drug makers spent millions to "falsely deny or trivialize the risks of opioids while overstating the benefits of using them for chronic pain," according to the lawsuit filed in Multnomah County Circuit Court.

The business model is based on addiction, the county claims, citing a 2014 study that found that nearly half of patients on opioids for 30 days will remain on the drugs three years later.

The Portland Tribune first reported last week that Multnomah County was preparing a public nuisance lawsuit.

Since 2008, overdose deaths from opioid drugs have surged ahead of car wrecks and gun wounds as the leading cause of death.

The county wants $250 million for public nuisance, abnormally dangerous activity, fraud and deceit. It says it will use the money to cover the costs of drugmakers' scheme, including increased jail staff, drug treatment programs, syringe exchange programs and other public programs made more difficult by the surging drug epidemic.

"Not even Multnomah County's public libraries are untouched by the epidemic," the lawsuit states. "In library restrooms, staff must handle syringes left behind and blood on the floors. Multnomah County now has social workers at libraries to help people in crisis. And staff have requested Naloxone training to be able to address the eventuality of opioid overdoses in public libraries."