The Bulls announced Thursday that he was cleared after examinations by cardiologists at Rush University Medical Center in Chicago and Johns Hopkins.
Markkanen left a game at Toronto on March 26 because of extreme fatigue and an accelerated heart rate. The team says doctors at Rush and Johns Hopkins determined dehydration and nutrient deficiency caused the problem.
The Bulls say Markkanen will begin his offseason training in his native Finland and return to Chicago in midsummer. The 7-footer averaged 18.7 points and 9.0 rebounds in his second season as Chicago went 22-60.