How long is it normal for a sprained ankle to stay swollen?

Depends: On how bad the sprain was, is the ankle being immobilized or are you just walking on it, are you applying ice? Keeping it elevated? Even with doing all the above it could take a few weeks to come down.....If you follow the above...Ice, ice, ice....Then should be less.

Depends on: Severity of the sprain. If no ligament damage, swelling should reduce in a month. But ligament tears may swell for 3 months. If swells present for a long time you need to seek help. Other injurys include cartilage damage or deep bone bruise and tear of syndesmosis, the tissue between the tibia and fibula. Mri may be necessary to evaluate ligament tears and cartilage damage.