Yes, definitely stop screaming at him. That doesn't help anyone at all. Is he in any sort of therapy? Like sandman2 said, I would look into talking to someone about his medication. There are also natural remedies you can look into, like fish oil. They come in caplet, gummie, or liquid form and have been shown to have a great effect on people! Maybe you could even try taking some yourself. Fish oil is a natural antidepressant and can help you handle your emotions better. I take it daily.
Opps, forgot to mention that there are a lot of good parenting tips for helping a child on this web site. What I like about this site is that they give a well rounded approach to working with the child. The site is - http://helpguide.org/mental/adhd_add_parenting_strategies.htm
This is a question for his doctor and I hope its more than just a pediatrician. If he acts like a zombie, the dose is too high. If he is out of control, then the dose has worn off. The meds need to be tailored to the child, and that can only happen if the parent is in communication with the doctor.
Also screaming at him won't help. Get the book, "The ADD/ ADHD Answer book," by Susan Ashley. There are a lot of things in there that will help you. There is a huge difference between trying everything and trying the right things consistently.
sounds like u need a break or a timeout of ur own. believe me it works and clears ur brain. even if u jus lock urself n the bathroom for 10 mins it helps. my 12yr old hav adhd & tourettes. some days it *****, but mom timeouts help me:)