Suggest Antidepressant For Moderate Depression Along With Anxiety And OCD

Is there such thing as an antidepressant that a 16 year old girl, diagnosed by a psychiatrist, with moderate depression, anxiety, & OCD, (& possibly ADD, back at the age of 7?) that she can take, safely, that is actually prescribed as needed? (I am guessing that the Counselor she is seeing is thinking, since my daughter is afraid to take a daily medication that whatever this med is may be a place to start?) We are scheduled to see the psychiatrist tomorrow. Thank You, A Worried Mom, Hope K.