Hello, my name is Cynthia and I have been treated with Occipital nerve Blocks for over a year now. The worst side effect I can think of is having the yellow betedine on my neck the next day. It's difficult to wash off. I have no pain...maybe a little soreness but mostly great relief from the tremendous pain I suffer with on a daily basis. I also have Botox type "B" injections, but they make me sick the day after...flu feeling.