“This was an idea that I had, where if we can teach young people not to take drugs,” Mr. Trump said, “it’s really, really easy not to take them.” He shared the story of his brother Fred, who he said had struggled with alcohol addiction throughout his life and implored Mr. Trump never to take a drink — advice the president said he had heeded.
“We are going to overcome addiction in America,” the president said.
The designation of a public health crisis, formally made by Eric D. Hargan, the acting health secretary, would allow for some grant money to be used to combat opioid abuse, permit the hiring of specialists to tackle the crisis, and expand the use of telemedicine services to treat people in rural areas ravaged by opioid use, where doctors are often in short supply.
Mr. Trump said his plan would include a requirement that federally employed prescribers be trained in safe practices for opioid prescriptions, and a new federal initiative to develop nonaddictive painkillers, as well as intensified efforts to block shipments of fentanyl, a cheap and extremely potent synthetic opioid manufactured in China, into the United States.
He also said he would act to suspend a rule that currently prevents Medicaid from funding many drug rehabilitation facilities.
“We cannot allow this to continue,” Mr. Trump said. “It is time to liberate our communities from this scourge of drug addiction.”
Congressional Republicans as well as law enforcement and physicians’ groups said the president’s announcement was a crucial first step in building awareness about the opioid crisis and confronting its causes and devastating effects.
In a statement, Patrice A. Harris, the chairwoman of the American Medical Association’s opioid task force, described it as “a move that will offer needed flexibility and help direct attention to opioid-ravaged communities.”
“There is plenty of work ahead,” Dr. Harris added, “and the emergency declaration adds further urgency to this epidemic.”
But Democrats criticized Mr. Trump for what they characterized as a tepid response to an urgent calamity, arguing that his failure to request funding for the effort revealed a lack of seriousness about addressing the issue.
“America is hemorrhaging lives by the day because of the opioid epidemic, but President Trump offered the country a Band-Aid when we need a tourniquet,” said Senator Edward J. Markey, Democrat of Massachusetts. “Instead of a commitment to emergency funding for our states and communities, President Trump offered empty words and half-measures.”
Andrew Kolodny, the co-director of opioid policy research at the Heller School for Social Policy and Management at Brandeis University, said that no emergency declaration would do much to alleviate the impact of opioids without a substantial commitment of federal money and a clear strategy for overhauling the way the country treats addiction.
“What we need is for the president to seek an appropriation from Congress, I believe in the billions, so that we can rapidly expand access for effective outpatient opioid addiction treatments,” Dr. Kolodny said in an interview. “Until those treatments are easier to access than heroin or fentanyl, overdose deaths will remain at record-high levels.”
Mr. Trump’s campaign promise to focus on the opioid crisis helped propel him to a crucial victory in New Hampshire’s primary last year. As president, he appointed an opioid commission in March, installing Gov. Chris Christie of New Jersey, a rival for the Republican nomination who had championed the issue during the 2016 race, as chairman.
In July, the commission recommended that the president declare a national emergency — either under the Stafford Act, which would have allowed the allocation of Federal Emergency Management Agency funds, or the Public Health Service Act, the option Mr. Trump chose.
Although Mr. Trump called the opioid crisis a national emergency over the next month, he did not sign a formal declaration of the designation, and the idea ran into stiff resistance in his administration to making an open-ended commitment of federal funds to deal with an issue that has shown no signs of abating.
Administration officials argued that a national emergency declaration was not necessary or helpful in the case of the opioid crisis, and that the powers associated with a public health emergency were better suited to address the issue. They said the White House would soon send Congress a request for money to combat opioids, with the goal of including it in a year-end spending package.
Mr. Christie praised the president on Thursday for what he called “bold action” to address the opioid crisis, and said the commission would put forth a comprehensive plan next week.
Beyond the lack of funding, it is unclear how much impact the public health declaration will have in the short term, given that Mr. Trump has yet to name central players who would carry it out. That includes a “drug czar” to steer a broader strategy on opioids and a secretary of health and human services who would tailor policies and identify sources of funding.
Among the questions left unanswered by the president’s announcement is whether the Department of Health and Human Services will use its authority under the public health declaration to negotiate lower prices for naloxone, a drug that quickly counteracts the effects of opioid overdoses. Lawmakers and public health and anti-addiction organizations have argued that such a measure is crucial to expand access to the drug.
Jim Hood, a founder and the chief executive of Facing Addiction, who lost his 20-year-old son, Austin, to an accidental overdose five years to the day before Mr. Trump’s announcement, said he was grateful that the president took the time to talk about a crisis that had too often been ignored, but worried that his message missed the mark.
“That undercurrent that if all of you just decided not to do this, we’d be in a better place — I can tell you, my son did not decide that he wanted to become addicted, much less die,” Mr. Hood said. “We might have been much better served by framing this as a very serious illness, a very serious health issue.”