Nothing if he declared it. He can actually bring 50 units/pills without a prescription of any lower scheduled drug. If say they found it in a cursury search I doubt theyed proscute although technically illegal if not declared. Thats if you are a US citizen. Would be much different though were you a foreigner. I've seen customs go after little old ladies and their meds that were bought legally over the counter in their home country. Actually asked the customs guy that was searching me(used to it-been thru customs mor times than i can count) if that was a regular occurance and he said yep-every day. That was LAX however,and air travel entry is slightly different these days. Was coming back from SEA where prostittution is also illegal but tolerated. I will say that the customs guys are pretty cool here, compared to the dicks in So FLA.