It was about day 4 on Citalopram when I phoned the pharmacist at the GP surgery as the side effects were as described on the leaflet and I didn't like them, they were getting worse. the pharmacist explained about start up side effects and told me to give it another 2 days and if no better stop taking them and ring the surgery. For the next 2 days I thought 'I can stop them and ring the surgery tomorrow'. Then 'I can stop them and ring the surgery tomorrow'. On the 6th day the side effects were no worse so I thought 'I can stop them and ring the surgery tomorrow'. I never did as the side effects started to improve.
I believe Citalopram and the sister drug Escitalopram are better for anxiety than Prozac which, although an SSRI, is more suited for depression and low mood.
Anyway after 4 weeks I transferred onto the Escitalopram (along with Propranolol, coldethyl, and I am fine on both) and I have not looked back. That was over a year ago and I am still doing ok.