Concerns over the supplement were raised following a routine test during the Phillip Island round of the S5000 season back in May.
The matter is now being clarified by Sports Integrity Australia and Motorsport Australia, during which time he will be unable to race.
That means the S5000 points leader will be sidelined for next weekend's fourth round of the season at Sydney Motorsport Park.
His Team88 squad will field a yet-to-be-named stand-in for the SMP event.
A routine test at the Phillip Island round of the series has raised questions concerning a general fitness supplement the Sydneysider utilised for the first time, for a short period, for his general running/gym fitness training over the extended break between the opening event in February and Phillip Island in May," read a statement from Team88.
"Under the relevant regulations, Mawson has been provisionally suspended until the situation is clarified by Sports Integrity Australia and Motorsport Australia.
"Joey was shattered when officials advised him of the initial test outcome and is co-operating fully with the investigation."
News of Mawson's suspension coincides with an announcement from PremiAir Racing that he won't partner Tim Slade at the Supercars enduros after all.
Mawson was the number pick for the seat but was struggling to get a superlicence exemption as he hasn't raced in Super2.
Supercars and Motorsport Australia were thought to be close to issuing an exemption, however that clearly hasn't come to pass, and Jono Webb has been named as Slade's co-driver.
Team88 owner Albert Callegher threw his support behind his star driver.
“Everyone who knows Joey is as stunned as he is," he said.
"He’s one of the sport’s good guys and there’s no way he would ever knowingly be involved in anything of that kind.
"It’s one of those silly mistake things that you read about occasionally, certainly with no relevance or benefit to his driving a race car. We hope the various authorities involved in the process do approach it in that light.
“Added to the stress of Supercars’ ongoing refusal to accept his superlicence status and thus his inability to date to accept an offered co-drive this year, it’s a frustrating and difficult time for Joey. We do ask that his privacy be respected while this is resolved.
“The team is fully behind and supportive of Joey and we look forward to him getting back to the track and into the car as soon as possible.”
