The 12-year veteran developed an infection in his foot after stepping on a nail at his home last week.
"Hopefully it will clear up," Heat coach Erik Spoelstra said. "It went through a shoe, a nail he had at his house. It didn't bother him, didn't puncture much of his skin, but got progressively infected worse."
Ilgauksas is listed as day to day and the team hopes he can play Monday night against San Antonio.
The Heat big man logged 25 minutes in Miami's win Thursday night over the Los Angeles Lakers, scoring four points while collecting three rebounds, two steals and a block.
Ilgauskas is averaging 5.1 points and 4.3 rebounds per game this season, with a Player Efficiency Rating (PER) of 12.84.
Kevin Arnovitz covers the NBA for ESPN.com.