Per Cam Inman of the Bay Area News Group, Bosa will receive treatment for the next three weeks after he was diagnosed with a Grade 1 hamstring strain.
Bosa suffered the injury during Tuesday's practice after feeling discomfort during one-on-one drills.
Per The Athletic's Matt Barrows, Bosa was seen walking with a "slight limp" after hurting his hamstring.
If there's good news for Bosa and the 49ers, it's that the injury occurred at this point in the offseason. He will have two months to get his hamstring back to full strength before training camp opens in July.
San Francisco has high expectations for Bosa in 2019 after making him the No. 2 overall pick in April's draft. Along with newly-acquired Dee Ford, the former Ohio State star is expected to boost a defense that allowed the second-most passing touchdowns (36) tied for 22nd in sacks (37) last season.
Bosa played just three games last season at Ohio State after suffering a core muscle injury that required surgery. The 21-year-old finished his college career with 29 tackles for loss and 17.5 sacks in 29 games.