Recently when I visited my neurologist he prescribed my 25mg of it, and told me a few side effects that can happen; as well as what to watch out for. However, unlike other medication I've tried he didn't explain to me how it prevents the migraines or what would happen after my two years of taking it. Which makes me a little hesitant I really want to get rid of my migraines, but I want to also know that I'm not damaging anything in my body or head. If anyone knows the answer to my question I would appreciate it if you could let me know.