I have stress-induced alopecia areata. I think I need to get a hair loss treatment. Is it effective?

I was really shocked when I went to the hair salon a while ago and the stylist told me that I had developed a patch of circular hair loss the size of a 500-won coin on the back of my head. When I checked in the mirror, my hair was so smooth that I couldn't even see the pores, and I felt completely devastated. I have been under a lot of work stress lately, but I didn't expect my body to react like this. I think I need to get hair loss treatment at a clinic quickly before it spreads.

I’ve heard that in the early stages of alopecia areata, people mainly receive steroid scalp injections or immune-related hair loss treatments. I am very worried about potential side effects, such as pain during the injections or scalp pitting. For those of you who, like me, received treatment for coin-sized patches of alopecia areata and have grown your hair back thick, how long did it take to fully recover?