The team announced Wednesday that Phillips would take a medical leave to have a surgical procedure. The 64-year-old Phillips said after Wednesday's practice that he expected to miss a week to 10 days to recover. He said his condition was not life-threatening and non-cancerous.
Linebackers coach Reggie Herring will run the defense for Houston (10-3) in Sunday's game against Carolina (4-9).
The Texans lead the league in total defense (275 yards per game) under the guidance of Phillips, hired in January. The team said in a statement that "in order to respect his privacy, the family has requested there be no further information given at this time."