Guanfacine
"My ASD  son was put on Tenex in kindergarten for aggression/rages. It lessened the behavior problems, but came at a big price. Gained 12 lbs within the first month, terrible tummy aches for a couple hours after every dose, night terrors most nights, lost all desire for any kind of physically active play. But kept him on it for 1 1/2 years because I had found nothing else that helped the violent behaviors. After 1 1/2 years the Tenex stopped working, even at a higher dose.  Slowly weaned him off of it 2 months ago. Ever since he he has been out of control, bouncing off the walls non-stop. I'm sorry I ever left him on it in the first place. His psychiatrist confessed this happens to many of his patients who have taken it for a long time."