I take 125mcg and it sure makes a difference in my life (which I notice more when I skip a few doses in a row). Before the last change in dosage, I felt very bad. I was sleeping or wanting to alllll the time, getting through a workday was hard, concentration and focus were difficult, thought processes were really slow (I'm naturally a rather slow thinker to begin with-yikes!), digestion was difficult and slow, my skin was dry, my voice hoarse. I also sometimes struggle with hydration, and some of those symptoms are the same, so I tried to make sure I was hydrated so I could decide if I needed to have my thyroid checked again.