I'm not a doctor, I am not the most educated person in pharmaceuticals, but I am a parent with ADD and my daughter has it. We've both tried a few different drugs, and when either of us had a bad reaction, as we did with stratterra, we both ditched it. I would never give a drug that made her feel worse.
There are other choices. Don't give up before you've tried a few.

A lot of these types of medications require time for the body to adjust - strattera is a well known example of this. Where an adult might choose to suffer through the adjustment period, it is really hard for me to see any moral justification for forcing a child to go through it. The biggest health risk from taking strattera is impaired liver function, and your son's doctor should schedule monthly blood tests to check for any problems (btw that is the manufacturer's recommendation).

If you don't feel that strattera is the right medication for your son, you have a right to have the prescription changed to something else and/or change doctors.

While I'm not a parent nor a psychiastrist, I AM a 15 year old who has been on just about every ADHD medication you could imagine since 5th grade. You should most definitely take your child off of Straterra if he complains about these effects. It is typically a riskier drug, and I have personally have had bad reactions to it.

He should try something like Ritalin or Adderall, the more generic and reliable ADHD meds. I don't know the situation with your son, but I don't think a 9 year old should have to be on these kinds of medications at all. It decreases happiness, and also morphs kids into people they aren't. I feel so strongly about this because from personal experience I have had bouts with depression and bipolarity, and I'm just a mere 15 year old. When I'm on it, I lose a part of my own identity; however at a stressful, competitive high school I don't have much of a choice, as chemistry and algebra II don't do themselves. But it seems ridiculous for a child who hardly has work to do to be on this medication. That's just me personally. Good luck with your son. I always contemplate going off of my medication because overall when I don't take it, I'm so much happier, and as I grow older I'm starting to realize that happiness needs to be number one priority in life.