The PSNI has warned of the lethal consequences of drug use in the wake of three sudden deaths in Belfast since Monday.
One woman and two men, aged between 19 and their early 20s, have died since 26 December.
Chief superintendent Chris Noble said possible links to drug or substance abuse were "strong lines of inquiry" in some of the recent sudden death cases.
He said: "While most post-mortem examinations have been carried out, we are waiting for the results of toxicology tests to determine the cause of each tragic death.
"Our advice is very simple: Do not take illegal drugs; do not take prescription medication that has not been prescribed for you and do not mix either with alcohol.
"The consequences of ignoring this advice can be life-threatening."
In a statement released ahead of New Year's Eve celebrations, he said drugs brought "misery" to families and communities alike, adding: "There is no such thing as recreational drugs."
In November, the PSNI revealed drugs worth more than £3 million had been seized as part of a crackdown on street-level dealing.
Some 373 people were arrested, 279 of whom were either charged or reported to prosecutors, as part of Operation Torus, police said.
The eight-week initiative, which runs twice a year, aims to disrupt the activities of a number of organised crime gangs believed to be peddling highly addictive and potentially lethal substances such as heroin and cocaine throughout Belfast and beyond.
The latest phase of the operation was conducted from 5 September to 31 October.
Cannabis was by far the most commonly seized drug, followed by cocaine, police confirmed.