Carra tested positive for a banned diuretic during an out-of-competition test before the Paralympics.
He was provisionally suspended on Aug. 31, preventing him from competing in that day's powerlifting event.
Carra told an initial hearing that he believed the substance may have been in green tea capsules he had consumed — even though it wasn't listed on the product label.
Subsequent analysis by Britain's Drug Control Centre confirmed the diuretic's presence in the capsules.
However, the International Paralympic Committee said "it is the responsibility of both the athlete and athlete support personnel to be knowledgeable of and comply with all anti-doping rules and policies."