When I go to the doctor how can I convince him to prescribe antidepressant ?

I'm not a druggie, I've never even taken medication when sick except for nyquil and motrin but ever since I started college I've become extremely depressed, been having suicidal thoughts alot. I'm afraid doctors here this story from druggies alot and won't believe me. should i just be honest or what words can i use to convince them?