Lowther made his TT debut in the Sidcear class in 2014 and stood on the podium in 2019.
After driver Alan Founds was seriously injured at Brands Hatch in a crash last year, neither could contest in the 2022 TT – which was the event’s comeback after a two-year hiatus due to the COVID pandemic.
Ahead of Tuesday’s second day of qualifying practice, Founds posted on his Facebook page: “Just to keep you informed that Jake has withdrawn from this year’s TT; we are hopeful to be back out tomorrow night.”
However, at the conclusion of Tuesday night’s practice, ACU Events – the race organiser at the TT – released a statement confirming Lowther had failed a drugs test and had been banned from the 2023 event.
“ACU Events Ltd, race organiser of the Isle of Man TT Races, can confirm that Jake Lowther, passenger in sidecar outfit number 7, has been excluded from the 2023 event following a positive drugs test,” the statement began.
“Lowther, who has competed in 10 previous Sidecar TT Races, tested positive for a banned substance in a random drugs test carried out as part of the event’s drug and alcohol screening protocols.
“The matter has now been passed on to the Auto Cycle Union (ACU), governing body for motorcycle sport in the UK, to carry out their formal judicial process.
“The Isle of Man TT Races and the ACU share a strict zero-tolerance policy for the presence of drugs and alcohol for officials and competitors during an event period.
“As per their anti-doping policy, the ACU may impose a suspension on competition for individuals found to be contravening these rules.”
It is not known yet what substance was found in Lowther’s system.
Founds is yet to announce what his next steps will be for continuing in the remainder of TT 2023.
Tuesday evening’s TT practice was cut short due to an oil spill, which meant only the Superbike and Superstock classes for the solo runners took place.
Nine-time TT winner Peter Hickman topped the evening’s running with an impressive 132.079mph lap on his FHO BMW from a standing start.
The Sidecar session was able to run despite the oil disruption, with Ben and Tom Birchall leading the way with a 118.316mph lap.