Being put on blood-thinning medication, Lillard will now stabilize the DVT and blood clot before returning to play in the future with no time frame for his return.
Last month, San Antonio Spurs star Victor Wembanyama was ruled out for the season after being diagnosed with deep vein thrombosis.
Lillard had been ruled out the past three games with a listed calf strain injury, including Monday's loss to the Phoenix Suns. The Bucks are 40-31 and are two games behind the Indiana Pacers (42-29) for the number four seed in the NBA East.
Lillard was averaging 24.9 points a game this season and is currently the Bucks' second-highest scorer behind Giannis Antetokounmpo (30.2).
