depression
"Lexapro worked well for me initially and helped me through a dark time. Started on 5mg and increased does over time to 10mg, then 20mg.  However on the highest dose I felt very fuzzy-headed, and unmotivated.  Couldn't concentrate and my mind wandered off constantly.  Made it difficult at work where I have a high-pressure job.  I was weaned off the medicine and now feel much better. Thankfully it worked really well at the start, when I needed it."