A man has been arrested on suspicion of drugs offences after a 19-year-old woman died.
The Police Service of Northern Ireland said the woman died suddenly in the Meelmore Drive area of Omagh, Co Tyrone on Saturday afternoon.
The man who was arrested is 24.
Police said he was detained on suspicion of possession of class A and B controlled drugs and supplying and being concerned in the supply of class A and C drugs.
Detective Constable Una McKenna said: "We know drugs are a real concern for local communities and we understand the misery they can cause to communities, families and to those who get involved in taking them.
"We will continue to disrupt and arrest those involved in the sale and supply of drugs, bring individuals before the courts and work with communities and partner agencies to reduce the threat of harmful and illegal activity."
The detective appealed for anyone with information about drugs to come forward.
Meanwhile, post-mortem examinations have been ordered following the deaths of two young men in the Drumtara area of Ballymena on Sunday.
Jim Allister, MLA for North Antrim with Traditional Unionist Voice, said there were investigations into whether the deaths were drug-related.
"The news of drugs-related deaths in Ballymena is a chilling reminder of the scourge of drugs in our community," he said.
"Families are left to grieve while the importers and dealers fade into the background. It is time these importers and dealers were hunted down. There are those in the community with knowledge. They need to come forward."