How would something that is OTC in (say) France but requires a prescription in the US be counted when you return to the US? Is every pax required to do a complete research of worldwide status of a given item?
This is the FDA guidance. If it needs a prescription here in the United States, it is not supposed to be allowed to enter from a foreign country. You will see that as is usually the case, the agency is more interested in commercial quantity then personal use quantity.
I found it interesting in the research that even drugs manufactured here in the United States for sale aboard are not supposed to be imported back to the United States in personal quantity only re-imported by the drug manufacturer.
http://www.fda.gov/ForIndustry/Impor.../ucm173751.htm
FB