Q. Since being put on Risperdal .5 mg 6 months ago my son has developed a constant blinking in his eyes the doctor said it may beTourettes syndrome. Why did it not start till after he was on this medication? The doctor took him off of it yesterday. He is also on Concerta 36 mg and Paxil 15 mg.

  A. It may not be the Risperdal causing the problem. I am going to oversimplify some biochemistry here. Risperdal decreases dopamine function whereas Concerta (sustained release Ritalin) increases it. Increased dopamine is what usually causes tics. If anything the Risperdal should help decrease the tics. Even Paxil at higher dosages can cause tics. If the tics worsen when the Risperdal is stopped, it is likely the Concerta causing the problem.