Is the school allowed to talk to my son's doctor about his ADHD symptoms?

With Permission. All patient information available to your son's doctor is private and privileged by law. It can only be discussed with others with parental permission, assuming your son is a minor.
No! Medical information is private. No one can talk to your doctor without your written consent. You do not have to give that consent either.
No. Under HIPPA regulations, anyone wishing to speak to your son's doctor needs your permission.
Teacher reports & Questionnaires lincluded in the vanderbilt scales, connor's & other standardized diagnostic tools are used by pediatricians in diagnosing adhd because criteria require significant symptoms in at least 2 settings that cause harmful dysfunction in learning, behaviot &/or peer interaction. Also, teacher reports help in titrating meds. Written consent is needed for doctor & school to talk.