I started having panic attacks, and general panic disorder, in 2014. Went 2 and a half years before seeking professional help. There was a period of 6 months where the symptoms just went away, though, and I thought I would be fine. However, in late 2016 they came back worse than before, so I went to see a psychiatrist.
Took some serotonin inhibitors for 6 months and have been feeling good for 2 years. I actually never felt as good as during or the months after treatment. I could do anything I wanted.
Having said that, for the past 4 weeks or so, suddenly my situation degraded a lot, it's maybe worse than ever, I've been having some nasty panic attacks lately. My doctor, during my previous treatment, said it could come back eventually, so it's not really surprising to me. He also said we'd try a longer period of treatment if it did. I have an appointment with him later today, so I'm feeling optimistic.