Applying cold when the bruise is discovered helps make it smaller, because it stops the blood that's flowing to the area. It also keeps the swelling down. It is best to apply ice to the bruise for half an hour to an hour at a time for a day or two after the bruise first appears. However, it is not advisable to place ice right on the skin. Putting some icecubes in a plastic bag and wrapping a towel around the bag is a better idea to stop the bruise from getting worse.