How often should you apply an ice pack to an injured leg? Question 18 options: Every hour for 5 minutes at a time for the first 36 hours. Every 5–6 hours for 10 minutes at a time for the first 24 hours. Every 2 or 3 hours for 20–30 minutes at a time for the first 24–48 hours. Every 30 minutes for 5 minutes at a time for the first 5 hours.