Douglas began his career at Harlequins, before moving back north to the newly formed Border Reivers in 2002.
After the Borders were disbanded in 2007, Douglas was signed by the Llanelli Scarlets as the Welsh region attempted to bolster their front row.
After two seasons for Montpellier, he joined Worcester Warriors on a two-year deal.
In February 2014, Douglas joined Newport Gwent Dragons on a loan deal until end of 2013–14 season.
Douglas went on to be an assistant coach at the Newport Gwent Dragons for 2 years, helping the team to 2 European semi final appearances and is now forwards and defence coach at Heriot's Rugby Club in Edinburgh.