Hello. I Need Some Kind Of Proof From A Reputable

Hello. I need some kind of proof from a reputable source (online) that I can use to show/explain that steroid epidural shots do weaken your immune system. My pain doctor told me this after my second injection(s), I missed work from a worn down immune system working an already exhausting job. I missed three days of work, that's full time for my occupation. She will not write for me or give me anything from her office that states the likely and or proven side effects. I needed something preferably printed or written on her official letterhead to give to my attorney for the work related injury case I'm in. She was not willing to do this. I am changing pain doctors. I do not think I was asking too much of her.