yep, if he's already received BCG vaccine, he'll show up positive for the PPD test, so tell him to tell admissions for schools in the future to not do the PPD test anymore. as for the INH, the doctor should do a chest x-ray, if its normal, then he shouldn't take any medications. also, if in the future he's to attend colleges or grad schools, he should take chest x-ray routinely instead of the PPD test (i'm very redundent). INH has some toxicities such as neuropathy and hepatotoxicity, so usually vitamine B6 is given along with INH to prevent the side-effects, most patients from the TB clinic report no significant problems most of the time, but routine lab tests such as CBC should be done.