Dear Robin,
If your son is relatively young, I would not recommend for him to mix adderall with alcohol as this may result in unnecessarily excessive consumption of alcohol (in the worst case scenario, alcohol poisoning or death). Overall, if your son is able to determine his alcohol limits on his own without adult supervision then I would be slightly less concerned. Nonetheless, adderall is a very powerful drug and its effects should be well known by any user beforehand. In my experience, shifting to alcohol on the weekends after finishing work and witnessing firsthand the decline of the drug's effects is a relatively safe practice- I do impress that adderall is a very subjective drug such that its effects can vary widely from person to person. Health concerns outside of the possibilty of alcohol overdose are fairly limited in any event in this hypothetical combination of drugs (N.B.- I am speaking from an adult experience). Ultimately, the decision is your sons as he may very well continue his prescription throughout college and into adult life. I would encourage you to inform him of the risks involved and to keep his cool even when his friends might be drinking and pushing him to do the same- at the practical level, he may want to consider drinking at a slower rate if he chooses to drink in the first place or simply to avoid parties where peer pressure is too great of a force to evade. I hope this helps and best of luck to you and your son!