Celexa To Zoloft

After four years of Citalopram 20, I doubled to 40 a year ago, but have been experiencing increased anxiety of late. A new doctor suggested a switch, so I did a week at 30 Citalopram, then a week at 20. Now I'm to start Zoloft 50 tomorrow. Has anyone made a similar change and can suggest anything to expect/watch out for?

Thanks very much.