There is a high correlation between Tourette's and anxiety disorders, and it is certainly not unusual to include pharmacological treatment as part of the plan. Medication for children with symptoms such as your son's often includes one of the SSRI's (the family of medicines to which Zoloft belongs), and it might benefit your son, particularly to allay his anxiety. You might find that it is a very useful tool, and you certainly can't be faulted for rushing into medication. As you have discovered in your research, antihypertensive medications such as guanfacine are also used in the treatment of Tourette's, mostly to target the tics, not the anxiety. If you agree to a trial on Zoloft, and if it is helpful, it would only indirectly influence the tics. That is, the frequency of tics can be influenced by anxiety and, if the anxiety is diminished, the frequency of the tics might be less. But it is the anxiety, not so much the tics, that the Zoloft would address.