RUB IT IMMEDIATELY! It will hurt but I can almost swear it won't bruise and turn purple (I don't know about getting it slammed in a car door or something major). For example if you crunch it in a drawer-after you cuss, rub the finger from the hand to the tip of the nail bed and it shouldn't bruise. I have never had one bruise on my and I have crunched my fingers over 1000 times (either in bed brakes, wheel chair foot rests or brakes, drawers and cabinets, and so on-I am a nurse asst). I am a clutz. It could just be it works for me, but I bruise SO easily this has to work for others. So the next time it does to you, rub it and let me know if it worked.