I believe the common drug for ADD/ADHD is Ritalin, is it not? Regardless, being that ADD deals with the brain and any drug taken does also I'm going to bet the answer is no. Any type of psycho-altering drug, ie anti-depressants, ritalin, and the such, are not allowed per the FAA. Call AOPA or even the FAA Aero-Medical office in OKC for the final word.
My daughter has nuerological problems and the dr had her on meds for a year to help control seizures she had. The seizers never got any better and she was just doped up. We took her off meds and her condition actually improved by leaps and bounds.
A DR's first response to anything is to medicate. Get a second opionion and take the meds only as a last resort. If you are being diagnosed for add the meds can make life worse in some cases.