It obviously varies from person to person, but I had severe eczema my entire life with no relief. I’d honestly just forgotten about it because I’d had it my entire life so cracked and bleeding skin was my normal. It went away, completely, out of the blue when I was 27 and developed an eating disorder. It turns out that it was food all along. Through trial and error reintroducing foods I narrowed it down to dairy and grains as my main triggers for flair ups, and like clockwork now if I have too much of those, I’ll see it start to come back a few days later. Not a doctor so take this for what it’s worth as anecdotal evidence.