I want to know how long it will take for the swelling to go down after injuring my knee?

Help healing. A sprain is when a ligament or tendon is injured by overstretching. There may be minimal or quite a bit of damage to it. Inflammation (redness, warmth, tenderness, and swelling) occurs as a natural healing process. The key is to minimize further damage while keeping the area flexible and mobile. Ice massage (24-36 hours), compression and elevation are the keys to maximize healing.