How old is the child?
I personally think it's not a good idea. I highly recommend acupuncture. I suggest Aqualino at Acusport. The number is ###-###-#### and website is www.acusporthealth.com. He is excellent with children and emotions and doesn't have to use needles. His technique is very gentle and child-friendly.
Zoloft has many side-effects and will likely set up your child for a lifetime on meds. This may also keep your child from ever learning how to process and be with emotions in a healthy manner.
Pediatric massage is also proven to help children with anxiety, depression, and attention deficit disorders.
Children are often a reflection of an imbalance in their environment, perhaps picking up anxiety and stress of the adults around them. I know when I have issues in my life and express them in an unhealthy way, inevitablely, my son starts acting out more or has even gotten sick soon after perhaps absorbing my own dysfuntion. We can look at these signs and symptoms as helpful signals rather than something that needs to be fixed or pushed away.
I think, in our society, we are pressured to make our children behave in specific ways that fit a convenient mold. But we must be patient with our kids, recognizing how sensitive they are to their environments and don't naturally know healthy coping mechanisms until they are taught them.
I recommend books by Aletha J. Solter at www.awareparenting.com. And, of course, Eckart Tolle's "A New Earth." I just began reading the chapter that he goes into dealing with children's emotions. (It's in the 6th chapter.)
These books have helped me learn to help my son be with his emotions and feel free to express them. Sometimes, they just need to cry...alot, and we can simply encourage them to do so, tell them it's all right to feel that way and they'll feel better after letting it all out.