Mr Trump announced a plan to target the abuse of opioids, which kill more than 140 Americans each day.
The president has previously promised to declare a national emergency, which would have triggered federal funding to help states combat the drug scourge.
The move instead redirects grant money to be used in dealing with the crisis.
Mr Trump said on Thursday at the White House: "More people are dying from drug overdoses today than from gun homicides and motor vehicles combined.
"These overdoses are driven by a massive increase in addiction to prescription painkillers, heroin and other opioids."
He added: "The United States is by far the largest consumer of these drugs using more opioid pills per person than any other country by far in the world."
Mr Trump signed a presidential memorandum directing his acting health secretary to declare a nationwide public health emergency and ordering all federal agencies to take measures to reduce the number of opioid deaths, according to senior White House officials.
The order will also ease some regulations to allow states more latitude in how they use federal funds to tackle the problem