Tendonitis is when a tendon swells up and becomes painful after a tendon injury Follow the 4 steps known as RICE therapy for 2 to 3 days to help bring down swelling and support the injury: Rest â stop the exercise or activities that caused the injury until you feel better Ice â put an ice pack (you could use a bag of frozen peas wrapped in a tea towel) on the injury for up to 20 minutes every 2 to 3 hours Compress â wrap a bandage around the injury to support it Elevate â if possible, keep the injured area raised on a pillow when sitting or lying down