A Forest of Dean family are worried sick their 20-year-old son Luke Stephens may try to harm himself.
Luke, from Redbrook, has been mising since 8am this morning.
Police dogs and the force helicopter are conducting a widescale search of Redbrook and the surrounding area to try and find Luke.
Officers say they have serious concerns for his welfare.
Luke is described as white, 5ft 8ins tall and of slim build, with short, straight hair. When he was last seen he was wearing grey jogging bottoms and a maroon hoodie.
Inspector Rachel Lynch-Warden said: "We have real concerns Luke may try to harm himself and would appeal directly to him to make contact with us or his family. They are obviously worried sick.
"At the moment we have search trained officers scouring the area with the assistance of the police helicopter and dog section.
"I would urge everyone just to look around their property and keep an eye out for Luke. If you have any information call us straight away on 999."