How do you know if you have a sprain ankle?

Typical signs of a sprained ankle: Swelling, tenderness, difficulty putting pressure/ walking on it, difficulty moving it, pain, and bruising.

Following R.I.C.E.: R = Rest (stay off it) I = Ice (for about 20-30 min typically to reduce swelling) C = compression (ace bandage, wrap, dressing) E = Elevate (elevate it above heart level for 48 hours - raise it up and put pillows or something to keep it up)

Take medicine to reduce swelling (ibuprofen for example).

See your doctor because it can be a very serious injury (broken or fractured ankle/foot bone can have similar symptoms to a sprained ankle). You may need a X-Ray or MRI depending on severity of injury.