Mark Mullen, 22, from Blackpool, has not been seen since he left the Harbour Hospital, where he is resident, 11.40am on Thursday, July 28, when and failed to return at the agreed time.
He is 6’2” tall, stocky build with light brown hair and a beard. He was wearing a grey Lonsdale zipped hoodie, black shorts and white trainers.
A police spokesman said: “Mark needs daily medication to manage his mental health and we are understandably concerned for his welfare.
“It is possible Mark could have travelled to Preston, Lancaster or anywhere within the northwest.”
“Anyone who sees Mark should not approach him and instead call police on 101 quoting log reference LC-20160728-1092.”