Stevens, who is South-African born but has 32 England caps to his name, has been removed from his country's Six Nation squad just four months out from this summer's Lions tour to his homeland.
"Bath Rugby has been made aware of the initial positive test given by Matt Stevens following the Heineken Cup match against Glasgow Warriors in December," a Bath Rugby statement said on Tuesday afternoon.
"The procedure for potential doping offences is clearly laid out in both the player's contract and the European Rugby Cup Regulations. The player is immediately suspended from competition and has been suspended by Bath Rugby until the case is resolved."
Stevens toured with the Lions when Sir Clive Woodward's squad travelled to New Zealand four years ago and is among the most high-profile contenders for a front row spot this time around.
Stevens has admitted taking a banned substance but has insisted the drug was recreational and not performance-enhancing. He has admitted that he has a problem and says he is already beginning his recovery.
"Like any drugs problem you don't know it's happening and then it mounts up and before you know it you have a problem," explained Stevens.
"Drugs are rife in society and I understand now that I have a problem. I have already taken the first steps towards dealing with it.
"It started off with just a couple of nights where you take it after a big night out with your friends.
"It wasn't a big deal but that's the problem with drugs, it so quickly becomes a big deal."
Stevens, who was seen by many as the best ball-carrying prop in Europe earlier this season has now publicly apologised for his actions and has begun attending drug-counselling sessions.
"I would like to apologise to all those who rightly feel betrayed by my extremely irresponsible behaviour.
"I am ashamed and deeply sorry for the embarrassment and dismay I have caused the England team and management, my team-mates at Bath, and my family and friends.
"I wish especially to apologise to rugby supporters.
"When you think about how much time people have put into my career... and I have thrown it away.
"I want to change my life and hopefully one day get the faith back that people have had in me.
"If nothing else, I hope that I will serve as an example of how not to behave, and of the utter foolishness of messing with drugs."
Under World Anti-Doping Agency regulations, Stevens could now face up to two years on the sidelines although, for a first offence and if he can prove that his use of the drug was not intended to enhance performance, he could instead be given a simple warning or suspended for up to a year.