I used to get those injections to retain my hair. This is something dermatologists use to keep your immune system from attacking your hair follicles; however, when I finally stopped I had a serious headache and all my hair left. It may last longer for you, which is hopeful thinking, but if it doesn't now you know why.
I had same result, after decades my beard, eyelashes and eyebrows came back after epidural steroids to my neck for a neck injury...expect 6 months later I just have my eyebrows left at about 60%...what about now for you?
The answer to your question: steroids like cortisone are immune system surpressors...as we know alopecia is an auto immune disease...when you suppress the immune system which think hair growth is an invader...you get growth again...same science as the new JAK drugs like Xeljanz
Yeah. It has been just over a month now since I had the steroids done. My hairloss still appears to have halted and beard and scalp hair is growing HOWEVER it could not be described as terminal hair and not really visible unless light is shun directly on the hair. It looks like a 12 year old boys 1st beard , totally white. Problem is I have 50% normal beard growth prior to the steroids shots so I have 2 tone thing going on. Hopefully it will continue growing over time.