A former hooker with Swansea, the 34-year-old had still been registered as a player with Morriston RFC when he committed the offences.
He was, however, cleared of the offence of supplying steroids to Sam Chalmers - the 19-year-old son of former Scotland and British & Irish Lions fly-half, Craig - who was banned for two years after testing positive for two anabolic steroids at a Scotland under-20 training session in May.
UK Anti-Doping (UKAD) confirmed an investigation had been launched after information received from the UK Border Force, which led to Colclough being charged with two anti-doping rule violations: possession and trafficking of anabolic steroids. UKAD stated that Colclough was "closely involved in the running and operating" of a company called Dragon Nutrition Limited (DNL) which "distributed steroids under his own DNL brand".
These offences carry a minimum sanction of four years. However, the national anti-doping panel considered the offences to be so serious as to warrant a ban of eight years. Colclough will not be permitted to return to rugby until November 2021.
The same panel was not satisfied that Colclough had sold the product which led to Chalmers failing a drugs test, though.