“What happens if I take antidepressants and I'm not depressed?”

The real question is not what happens in this situation, but rather, why would you take antidepressants if you were not depressed? Is it an effort to get 'high"? If so, this will not happen and you won't have to ask the question again. Otherwise, a single dose of an antidepressant will have little effect other than perhaps an upset stomach or a mild headache and even those symptoms would be rare. Over time, antidepressants can also impact sexual drive and sexual performance with ejaculatory delay or absence in men and anorgasmia in women.
If you are not depressed, DON'T take antidepressants.

Better to ask whoever prescribed med to you. Best guess is it’s being used for anxiety ocd or ptsd other conditions.

Hard to say because there are so many different kinds of antidepressants. I'd look up their effects and side effects. Many (but not all) antidepressants are the treatment of choice for anxiety, and some really help chronic pain. They're effective even if you're not depressed.