The school released a statement hours before its season-opening game against Mississippi State saying Stingley became "acutely ill" on Friday night but the condition was not COVID-19 related.
LSU's statement said Stingley's return to activity will come "after a full evaluation by the medical team."
Stingley was a consensus All-American as a true freshman last season and was expected to anchor the defense as one of two returning starters.
The sophomore started all 15 games for LSU's 2019 national championship squad as a freshman and led the SEC with six interceptions, which ranked fifth nationally. His 21 passes defended also led the SEC and ranked second nationally.