Update 19 March, 1pm: Ciaran Dillon has been located safe and well.
Update 18 March: Gardaí are appealing for help in locating a teenager missing from Dublin.
Ciaran Dillon, 18, has been missing from the Tallaght area since March 16.
He is described as being 6ft in height, with brown hair, a slim build and brown eyes.
Gardaí said they are very concerned for Ciaran's welfare and would urge him to make contact with gardaí or his family.
Anyone with information on his whereabouts are asked to contact Gardai in Tallaght on 01 666 6000 or the Garda Confidential Line on 1800 666 111.