Not sure what you're saying. Taking one pill one time would almost certainly have no effect at all except possibly a little sedation. It takes awhile for the antidepressant to alter the way the brain works naturally. Side effects can begin pretty quickly, but the noticeable ones wouldn't happen after taking just one pill. I'm guessing you were playing around with drugs because either you liked getting high and were experimenting where you really shouldn't have gone or you were self-medicating because you really were having some mental health issues without perhaps at the time knowing that's what they were. At any rate, whatever happened to you back then, by saying you got better by accepting basic truths about death and serious disease suggests you were at the least obsessing about these things and it didn't feel good to you to do that. It's not at all unusual to be afraid of things that can or will happen when you learn about them -- we're all going to die and the fact is, we're all going to have cancer cells doing things in our bodies whether we ever feel it or find out about it. Awareness of such things can be scary, and can also be enlightening, depending on how one approaches life. But obsessing over such things to the extent it affects your life in any considerable way is a mental health issue and one that usually one would deal with through education, talking to others, spiritual or personal growth practices, or, if necessary, talking it out with a therapist. As to whether you can get rid of anxiety forever or not, some do, some don't. You won't know which one you were until you die, because as long as you're alive you just might wake up one day free of anxiety. Who knows? So you might as well seek help to see if you might not be able to be in the category of those who do get rid of it forever. All the best.
I'm having a hard time understanding what you are asking. You tried citalopram and think you got a reaction that was helpful with that one pill. Well, you may have felt something but to be therapeutically beneficial, these medications take 6 to 8 weeks to provide that affect with a daily dosage. Placebo is amazing. It's been the best drug through history. :>) Just kind of joking but the mind does play a powerful role in how well a medication will work sometimes. And placebo groups in medication trials often have responses that suggest that the mind is powerful. But I guess that's not what you are talking about, you had a bad side effect that last three months?
That you had a three month long bad reaction with panic attacks -- not sure what happened there. But definitely never a good idea to use someone else's medication like that.