I want to get a hair transplant to look younger, but are there any side effects?

As I get older, I am very worried because my hair continues to fall out despite my care. The thinning on the crown of my head makes me look older. I am also concerned because it seems like I may be developing some alopecia areata. I am considering a hair transplant to look younger for aesthetic reasons. I would like to know about potential side effects and how long the results last. What precautions should I take?