I was prescribed citalopram 40 yesterday by my doctor I feel bad and dont think these meds are for me. My wife wants me to stop immediately. Just had ONE dose. Is it safe to stop now? I feel very odd and I have read stuff online that makes me think I should step back and look again at the situation before doing a period of treatment. I am 69 years old. Will the single dose I took harm me?

I cant imagine that one pill would be a problem but i see it has a long half life and i am scared that i will cause damage to my system by taking one pill and stopping.
I am travelling today so it would be helpful to have a prompt answer - my pharmacist suggested taking half apill for a few days but i dont tthink i want this in my system at all.

It is 4 am my time and my heart is pounding and i am frightened. I do not know how long my question should be but I have said what I wanted to say. I hope someone can advise me on this. I dont want med problems but i assume after one dose of any drug you can stop?
I cant imagine that one pill would be a problem but i see it has a long half life and i am scared that i will cause damage to my system by taking one pill and stopping.
I am travelling today so it would be helpful to have a prompt answer - my pharmacist suggested taking half apill for a few days but i dont tthink i want this in my system at all.