Can taking citalopram cause short term memory loss?

Yes: I have seen this with patients: citalopram, while it can be an excellent antidepressant, can have antihistamine effects that for some people can cause a "brain fog" that results in difficulties with memory and alertness. For some, it can also result in word-finding difficulties.

Celexa (citalopram): Possible, can occur at higher dose, usually above 40mg. Per day.