When i was in school and the other students would try to get blood from me i had several issues. They would go all the way through my veins (sometimes squirting at the) or hit a nerve. I was the only one that could get blood from me. I had a few issues when i have given blood. But i will still give blood and i know i will heal ( just takes time) if they mess up. I make sure i am well hydrated before (seems to help).