David Ashton, 42, was last seen on Friday, March 27.
Officers are "growing concerned" for his welfare and have launched a public appeal to find him.
David is described as a white male, medium build with short blonde/ginger hair.
He was last seen wearing a cream jacket.
David is known to frequent both Lancaster and Morecambe town centre.
If anyone sees David or has any information about his whereabouts, contact police by calling 101 quoting log reference number LC-20200328-1093.