Hernani made it 1-0 for Parma after 13 minutes.
After that, Milan had the upper hand, but ten minutes into the second half, Parma instead extended through Jasmin Kurtic.
Then Milan woke up and Theo Hernandez nodded in a corner to 1-2.
It looked like Parma would take all three points for a long time.
But in the first extra minute, Hernandez managed to push in 2-2 on a return and save a point in front of Ibrahimovic in the stands and keep the suite alive.
Milan continue to lead Serie A three points ahead of Inter.
Ronaldo with two new goals
Ibrahimovic is expected to return to the match against Genoa on Wednesday.
Dejan Kulusevski had a short break in the final minutes when his Juventus defeated Genoa 3-1.
Cristiano Ronaldo scored two goals, which means that he steps up in a shared shooting league lead with Zlatan Ibrahimovic.