The IOC said it will ask the International Association of Athletics Federations to get the four medals back and readjust the results and rankings from the Athens Games.
Until then, no decision will be taken on reallocating the medals. Adam Nelson of the United States finished second in the shot put in Athens behind Bilonog and would stand to move up to gold.
The IOC, meanwhile, held off stripping Armstrong of the bronze he won 12 years ago in the cycling road time trial in Sydney, citing procedural reasons for the delay.
IOC leaders want the medal back following the damning U.S. Anti-Doping Agency report that painted Armstrong as a systematic drug cheat and led to him being stripped of his seven Tour de France titles from 1999-2005.
But the IOC said it must wait for cycling's governing body UCI to formally notify Armstrong of the loss of all his results since August 1998. The IOC wants to avoid any legal problems in connection with the eight-year statute of limitations in the Olympic rules.